# CycleCalcs Astronomy (remote · www.cyclecalcs.com) Astronomy: sun, moon, planet, eclipse, twilight and star position calculations. - Trust score: 68/100 (medium) - Change this week: +4 - Registry status: active - Liveness: live - Owner verified: no - Last scored: 2026-08-18 ## Components - remote · `www.cyclecalcs.com`: 68/100 (this document), [markdown](https://verifymcp.io/servers/com-cyclecalcs-astronomy/www.md), [page](https://verifymcp.io/servers/com-cyclecalcs-astronomy/www) ## Channel facts - Endpoint: `https://www.cyclecalcs.com/mcp` - Transports: `streamable-http` - Auth: `required` - Version: `1.0.0` ## Trust breakdown How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog) Scored 2026-08-18. - **Endpoint Security**: 66/100 - The endpoint's TLS certificate is valid, in date, and uses a strong key. - Authorisation not fully verified: no authorisation is required to call this server, and 11 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe. - HTTPS is enforced; there's no plaintext access path. - The HSTS (Strict-Transport-Security) header is present. - DNSSEC is configured correctly; the domain's records validate against the full chain to the root. - **Transport & Reachability**: 100/100 - Verified streamable-http transport via a live MCP handshake. - **Schema Quality & AI Usability**: 60/100 - AI-judged instruction clarity (excellent). - Context-footprint check failed: tool/resource definitions use about 5758 tokens (~523/item across 11 items; 11 tools + 0 resources), over budget; trim descriptions and params. - Usage-examples check failed: none of the tools include examples. - **Stability & Change Management**: 30/100 - Stability observed for 9 of 30 days with no destabilising changes; credit accrues until the full window elapses. - **Tool Coverage**: 100/100 - 100% of tools have a non-trivial description (not blank, and not just the tool's name). - 100% of tool parameters carry a description. - Structured output schemas are declared (100% of tools); any adoption earns full credit. - **Capabilities**: 100/100 - Implements a current MCP spec version (2026-07-28). ## Install ### Claude ```bash claude mcp add --transport http com-cyclecalcs-astronomy https://www.cyclecalcs.com/mcp ``` ### Codex ```toml [mcp_servers.com-cyclecalcs-astronomy] url = "https://www.cyclecalcs.com/mcp" ``` ### opencode ```json { "$schema": "https://opencode.ai/config.json", "mcp": { "com-cyclecalcs-astronomy": { "type": "remote", "url": "https://www.cyclecalcs.com/mcp", "enabled": true } } } ``` ### OpenClaw ```bash openclaw mcp add com-cyclecalcs-astronomy --url https://www.cyclecalcs.com/mcp --transport streamable-http ``` ### Hermes ```yaml mcp_servers: com-cyclecalcs-astronomy: url: "https://www.cyclecalcs.com/mcp" ``` ### Other ```json { "mcpServers": { "com-cyclecalcs-astronomy": { "type": "http", "url": "https://www.cyclecalcs.com/mcp" } } } ``` The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs. ## Changelog Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims. ### 2026-08-18 (score 68, +1) No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes. ### 2026-08-16 (score 67, +1) No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes. ### 2026-08-14 (score 66, +1) No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes. ### 2026-08-12 (score 65, +1) No change was recorded against any check on this day. Stability & Change Management went from 7 to 10. That category is still filling its 30-day observation window: 2 days of observed history at the previous scan, 3 at this one. The score rises as the window fills, whether or not the server changes. ### 2026-08-11 (score 64, +1) - [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server ### 2026-08-10 (score 63, 0) - [functional improvement] Stability: unverified → 0.03 - [functional improvement] Tool “astro_dark_window” now declares an output schema - [functional improvement] Tool “astro_eclipses” now declares an output schema - [functional improvement] Tool “astro_find_place” now declares an output schema - [functional improvement] Tool “astro_moon” now declares an output schema - [functional improvement] Tool “astro_moon_phases” now declares an output schema - [functional improvement] Tool “astro_planet_board” now declares an output schema - [functional improvement] Tool “astro_planet_events” now declares an output schema - [functional improvement] Tool “astro_positions” now declares an output schema - [functional improvement] Tool “astro_rise_set” now declares an output schema - [functional improvement] Tool “astro_sky_today” now declares an output schema - [functional improvement] Tool “astro_sun” now declares an output schema - [functional] First check of Tool coverage: 100 ### 2026-08-09 (score 63) First indexed and scored. ## MCP tools (11) ### `astro_sky_today` (~332 tokens) Sky snapshot for a place and moment One-call snapshot of the whole sky for a place and moment: moon phase and illumination, which planets are up and worth looking at, the next eclipse, and (with a location) sun times. Reach for this first when the question is broad, like "what is in the sky tonight". For solar-day detail use astro_sun; for choosing an observing night use astro_dark_window; for one planet's exact position use astro_positions. Input parameters: - `date` (string): ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): A whole-sky snapshot for one place and moment. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_sun` (~580 tokens) Sunrise, sunset and twilight The complete solar day for one location: sunrise, sunset, solar noon, day length, civil, nautical and astronomical twilight boundaries, and explicit polar day/night status at high latitudes. Location required. For a series, send start and end (step is whole days, e.g. "1d" or "7d"). For "is it dark enough to observe" prefer astro_dark_window; for a broad snapshot prefer astro_sky_today. Input parameters: - `cursor` (string): Opaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page. - `date` (string): Single day to report, ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OU… - `end` (string): Last day of a range. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `start` (string): First day of a range (use with end instead of date). ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that ran… - `step` (string): Range stride in whole days, e.g. "1d", "7d", "30d". Default "1d". - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): The complete solar day for one location, or one row per day in range mode. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_moon` (~534 tokens) Moon state and appearance The Moon at an instant or as a daily series: phase name and angle, illuminated fraction, distance, apparent size, libration, bright limb, and the next quarter phases. A location adds rise/set and altitude. For a calendar of new and full moons use astro_moon_phases; for the Moon's exact coordinates use astro_positions. Input parameters: - `count` (integer): Number of daily rows from start (alternative to end). - `cursor` (string): Opaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page. - `date` (string): ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the… - `end` (string): Last day of a daily series. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with D… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `start` (string): First day of a daily series. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with… - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): The Moon's state and appearance, or a sampled series in range mode. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_moon_phases` (~586 tokens) Lunar phase calendar Every new moon, quarter and full moon in a window (or the next few from a date): each with its exact instant, distance, apparent size, supermoon classification under both competing definitions, traditional full-moon name, and any eclipse falling on it. Use for "when is the next full moon" and phase calendars. For the Moon's state right now use astro_moon. Input parameters: - `count` (integer): How many phase events to return from the anchor date. - `cursor` (string): Opaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page. - `date` (string): Anchor date; the next phases follow it. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API re… - `end` (string): Last day of a window. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OU… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `phases` (array): Optional filter of phase kinds. Omit for all four. Example: ["full_moon"] for full moons only. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `start` (string): First day of a window (use with end). ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refu… - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): New, first quarter, full and last quarter moons in a date range. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_positions` (~661 tokens) Precise positions of bodies Exact positions for up to 20 bodies at an instant or over a time grid: right ascension and declination in both J2000 and of-date frames, ecliptic longitude and latitude, distance, and, with a location, altitude and azimuth with refraction stated per field. Use for "where exactly is X". Do not pass earth. For rise and set TIMES use astro_rise_set; for a visibility overview of all planets use astro_planet_board. Input parameters: - `bodies` (array, required): Bodies to report. Each entry: One of sun, moon, mercury, venus, mars, jupiter, saturn, uranus, neptune, pluto, or a fixed J2000 target as "radec:RA,DEC" with RA in hours (0-24) and DEC in degrees (-9… - `cursor` (string): Opaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page. - `date` (string): ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the… - `end` (string): Grid end. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE b… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `start` (string): Grid start (use with end and step). ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuse… - `step` (string): Grid stride, e.g. "1h", "10min", "1d". - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): Where each requested body is, at an instant or sampled across a range. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_rise_set` (~633 tokens) Rise, transit and set times Rise, upper transit, set and lower transit for one body at one location, with an explicit status at extreme latitudes (circumpolar, never rises) instead of missing values. Accepts fixed radec targets. For the Sun specifically, astro_sun returns richer twilight structure; for positions between events use astro_positions. Input parameters: - `body` (string, required): One of sun, moon, mercury, venus, mars, jupiter, saturn, uranus, neptune, pluto, or a fixed J2000 target as "radec:RA,DEC" with RA in hours (0-24) and DEC in degrees (-90..90), e.g. "radec:5.6,-5.4"… - `cursor` (string): Opaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page. - `date` (string): ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the… - `end` (string): Last day of a daily series. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with D… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `search_horizon_days` (integer): How many days ahead to search when an event does not occur on the requested day (high latitudes). - `start` (string): First day of a daily series. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with… - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): Rise, transit and set for one body, for a day or across a range. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_eclipses` (~619 tokens) Solar and lunar eclipses Solar and lunar eclipses: the next or previous from a date, or all in a range, with type, magnitude, obscuration, Saros series and global geometry. With a location it adds local circumstances, contact times, and an explicit visible-from-here answer; set visible_only to true to keep only eclipses visible there. NOTE: count applies per type, so count=3 with type "both" can return six events. Input parameters: - `count` (integer): How many eclipses PER TYPE to return. - `cursor` (string): Opaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page. - `date` (string): Anchor date to search from. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with D… - `direction` (string): Search direction from the anchor date. Default "next". - `end` (string): Last day of an explicit window. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses wi… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `start` (string): First day of an explicit window (use with end). ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range th… - `type` (string): Which kind of eclipse to report. Default "both". - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. - `visible_only` (boolean): true keeps only eclipses visible from the supplied location (requires a location). Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): Solar and lunar eclipses in a date range, optionally filtered to one location. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_dark_window` (~364 tokens) Dark moonless observing window The genuinely dark, moonless observing window for a night: astronomical night intersected with the Moon being down, ranked across up to 62 nights with a trend. The right tool for "when should I stargaze / photograph the Milky Way / observe deep-sky objects". Location required. For plain twilight times use astro_sun. Input parameters: - `date` (string): Night to start from. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `moon_illumination_max` (number): Treat the Moon as tolerable below this illuminated fraction (0..1) even when up. - `nights` (integer): How many nights to evaluate and rank. Default 1. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): The best genuinely dark observing windows across a range of nights. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_planet_board` (~365 tokens) All planets at a glance All eight planets in one call for a date and optional location: constellation, magnitude, apparent size, elongation from the Sun, morning or evening sky, retrograde state with the next station, rise/set, and a worth-looking-tonight assessment. The right tool for "which planets are visible tonight". For exact coordinates of specific bodies use astro_positions. Input parameters: - `bodies` (array): Optional subset of planets: mercury, venus, mars, jupiter, saturn, uranus, neptune, pluto. - `date` (string): ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API refuses with DATE_OUT_OF_RANGE because the… - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `sort` (string): Optional result ordering. Default is by distance from the Sun. - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): Which planets are worth looking at right now, and where. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_planet_events` (~683 tokens) Mercury and Venus apparition events The apparition cycle of the inferior planets as dated events: inferior and superior conjunctions, greatest eastern and western elongations, peak brightness (a Venus-only event: Mercury's brightness peaks behind the Sun where it cannot be seen), and the rare transits across the Sun. With no dates it also reports where each body is in its cycle right now: morning star or evening star, the conjunctions bounding the current apparition, and the live elongation, phase, magnitude and apparent size. The right tool for "when does Venus become the morning star", "when is Venus brightest", or "Mercury's next greatest elongation". For tonight's visibility of all eight planets use astro_planet_board. Conjunction instants use the classical heliocentric convention, named on each event. Input parameters: - `bodies` (array): Which inferior planets to report. Default both. - `cursor` (string): Opaque pagination cursor from a previous result's next_cursor. Send it with the same start/end arguments as the first page. - `date` (string): Anchor instant; with no start/end the response covers the next full synodic cycle from here. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Y… - `end` (string): Last day of an explicit window, exclusive. ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range the API… - `kinds` (array): Optional filter of event kinds. Omit for all. peak_magnitude only ever fires for venus; the transit kinds are body-specific and genuinely rare. - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `place` (string): Place name instead of lat/lon, as "City" or "City,CC" with an ISO country code, e.g. "Lisbon,PT". Resolved server-side; the response then carries a required GeoNames CC BY 4.0 credit in its attributi… - `start` (string): First day of an explicit window (use with end). ISO 8601 UTC date or datetime, e.g. "2026-08-06" or "2026-08-06T21:00:00Z". Omit for the current moment. Years 1700 to 2200 only; outside that range th… - `tz` (string): IANA timezone like "Europe/Lisbon" to render event times in local time. Optional; a resolved place supplies its own timezone. Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): Apparition events per planet in a date range: conjunctions, elongations, stations. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ### `astro_find_place` (~228 tokens) Place name to coordinates and timezone Resolve a place name to coordinates, region, country, IANA timezone and a stable place_id, or reverse-look-up the nearest places to a lat/lon. Results are GeoNames data (CC BY 4.0); the response carries the required credit in its attribution field, which must be preserved when results are shown. Note the other tools accept a place argument directly, so this is only needed to disambiguate a name, filter by country, or reverse-geocode. Input parameters: - `country` (string): Two-letter ISO country code filter, e.g. "US". - `id` (string): A place_id from an earlier result, to fetch that exact place. - `lat` (number): Latitude in decimal degrees, north positive. Send lat and lon together. - `limit` (integer): Maximum matches to return. Default 5. - `lon` (number): Longitude in decimal degrees, east positive (Lisbon is about -9.14). Send lat and lon together. - `query` (string): Place name to search for, e.g. "Springfield". Output parameters: - `attribution` (string): The credit line to display verbatim when rights is attribution_required. - `data` (object): Coordinates for a place name, or the nearest named places to coordinates. - `next_cursor` (string): Present only when more rows exist. Send it back with the SAME start/end arguments as the first call to get the next page. - `not_computed` (array): Data this API deliberately does not serve, and why. Present only when the question touched such a field. An absence named here is information: treat it as "withheld", never as "none exists". - `rights` (string): Either unrestricted, or attribution_required when third-party place data was used. When attribution_required, the attribution line must be shown. - `warnings` (array): Machine-readable notices about this answer. Present only when non-empty. Never changes whether the call succeeded. ## Diagnostics Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/com-cyclecalcs-astronomy/www#diagnostics ## Score history - 2026-08-18: 68 - 2026-08-17: 67 - 2026-08-16: 67 - 2026-08-15: 66 - 2026-08-14: 66 - 2026-08-13: 65 - 2026-08-12: 65 - 2026-08-11: 64 - 2026-08-10: 63 - 2026-08-09: 63 ## Links - Remote endpoint: https://www.cyclecalcs.com/mcp - Authorisation metadata: https://www.cyclecalcs.com/.well-known/oauth-protected-resource/mcp - Website: https://www.cyclecalcs.com/api/mcp.html - Changelog RSS feed: https://verifymcp.io/servers/com-cyclecalcs-astronomy/www.xml - Changelog JSON feed: https://verifymcp.io/servers/com-cyclecalcs-astronomy/www.json - HTML version of this page: https://verifymcp.io/servers/com-cyclecalcs-astronomy/www