Professor Otter
REMOTE · PROFESSOROTTER.COM
Free printable kids activities: word searches, mazes, color by number, sudoku and more.
Available components
Last scanned (16 hours ago)
Scores higher than 97% of remote servers
Reachable. Last reached 5 Nov 2026.
Category Education and Research
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. How we score → Why this is hard to score →
Endpoint Security80
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- No authorisation is required to call this server. Nothing on it is marked destructive, but we can't show that an anonymous caller can only read: full credit needs the server to list at least one tool and every tool to be verifiably read-only. We use a best-effort check of tool names and descriptions to tell read-only tools from tools that change things, so some genuinely read-only tools may not get full credit. Names that start with a read verb (get, list, read, search and similar) and accurate readOnlyHint annotations help. Meet that to earn full credit, or require authorisation. See how to fix → View diagnostics → Partial
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability84
- 100% of prompts and resources have a non-trivial description (not blank, and not just the item's name).Pass
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 1012 tokens (~144/item across 7 items; 6 tools + 1 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management100
- No destabilizing schema changes in the last 30 days.Pass
Tool Coverage97
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 91% of tool parameters carry a description.Partial
- Structured output schemas are declared (100% of tools); any adoption earns full credit.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 6 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 8 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
- Supports UI / widget rendering.Pass
Checks we ran (14)
- TLS certificate
- Authorization
- HTTPS
- HSTS header
- DNSSEC
- Transport
- Schema quality
- Stability
- Tool coverage
- Injection markers
- Destructive annotations
- Judged manipulation
- MCP protocol
- Capabilities
Does not apply to this hosted endpoint (2)
- Supply Chain SecurityScored on package channels only. This is a hosted endpoint, so there is nothing to install or inspect.
- Provenance & TransparencyScored on package channels only. This is a hosted endpoint, so there is nothing to install or inspect.
The score does not measure everything. What the score does not measure →
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 3 Nov 26 +1
- Stability: 0.97 → pass security
- 1 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 90 to 93. That category is still filling its 30-day observation window: 27 days of observed history at the previous scan, 28 at this one. The score rises as the window fills, whether or not the server changes.
- 29 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 80 to 83. That category is still filling its 30-day observation window: 24 days of observed history at the previous scan, 25 at this one. The score rises as the window fills, whether or not the server changes.
- 27 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 73 to 77. That category is still filling its 30-day observation window: 22 days of observed history at the previous scan, 23 at this one. The score rises as the window fills, whether or not the server changes.
- 25 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 67 to 70. That category is still filling its 30-day observation window: 20 days of observed history at the previous scan, 21 at this one. The score rises as the window fills, whether or not the server changes.
- 23 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 60 to 63. That category is still filling its 30-day observation window: 18 days of observed history at the previous scan, 19 at this one. The score rises as the window fills, whether or not the server changes.
- 21 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 53 to 57. That category is still filling its 30-day observation window: 16 days of observed history at the previous scan, 17 at this one. The score rises as the window fills, whether or not the server changes.
- 19 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 47 to 50. That category is still filling its 30-day observation window: 14 days of observed history at the previous scan, 15 at this one. The score rises as the window fills, whether or not the server changes.
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 5 Nov 2026 · Probed https://professorotter.com/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=*.professorotter.com | CN=YR1,O=Let's Encrypt,C=US | 4 Oct 2026 | 2 Jan 2027 | RSA 2048 | SHA256-RSA | 53afccea800516f6386086c0b4a68d92eff |
| SANs: *.professorotter.com, professorotter.com | ||||||
| CN=YR1,O=Let's Encrypt,C=US (CA) | CN=Root YR,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | RSA 2048 | SHA256-RSA | a20253f15f2691c05dc1ce13b9bcca4e |
| CN=Root YR,O=ISRG,C=US (CA) | CN=ISRG Root X1,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | RSA 4096 | SHA256-RSA | f24b6d17f9d9ad7cb1c9fea78782699f |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of professorotter.com. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | Trust anchor | 20326, 38696 | 8, 8 | Verified |
| com. | DS published | 19718 | 13 | Verified |
| professorotter.com. | No DS | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
| Header | Value |
|---|---|
| strict-transport-security | max-age=63072000 |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://professorotter.com/mcp | Verified | 200 | |
| http (plaintext) | http://professorotter.com/mcp | HTTPS enforced | 308 | https://professorotter.com/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
get_activity Get an activity ~84
Get one printable puzzle as Markdown (description, level, word list or color key) with its play URL and its PDF URL. A puzzle PDF has an answer key. A game or drawing practice PDF does not. Use an activity and slug from search_activities.
| Name | Type | Req | Description |
|---|---|---|---|
| activity | string | yes | – |
| slug | string | yes | Puzzle slug, for example "farm-friends". |
| Name | Type | Req | Description |
|---|---|---|---|
| activity | string | yes | – |
| level | string | yes | – |
| markdownUrl | string | yes | – |
| pdfUrl | string | yes | – |
| playUrl | string | yes | – |
| slug | string | yes | – |
| title | string | yes | – |
No examples provided.
list_activities List activities ~83
List the Professor Otter printable activities (word searches, color by number, coloring pages, mazes, dot-to-dot, drawing practice, criss-cross, word scrambles, spot the difference, sudoku, games, secret codes, bingo, nonograms) with how many puzzles each has, its levels and its topics. Start here to see what the site offers.
Input schema present but exposes no named parameters.
| Name | Type | Req | Description |
|---|---|---|---|
| activities | array | yes | – |
| levels | array | yes | – |
No examples provided.
list_products List shop products ~56
List the Professor Otter shop: printable PDF books, topic packs and the Everything Bundle, with prices and availability. Checkout is a browser page on the shop. Send the person there; never collect payment details or try to buy for them.
Input schema present but exposes no named parameters.
| Name | Type | Req | Description |
|---|---|---|---|
| checkout | string | yes | – |
| products | array | yes | – |
| shopUrl | string | yes | – |
No examples provided.
make_word_search Make a word search from a spelling list ~258
Turn a list of 4 to 20 words, like a child's spelling list, into a word search they can play in the chat, with a link to print it as a PDF with an answer key. Paste the list as one string or pass the words as an array. A word longer than the level's grid makes the grid grow to fit it. If the list breaks a rule (too few words, a word over 20 letters, a word inside another), the error says what to fix.
| Name | Type | Req | Description |
|---|---|---|---|
| level | string | – | easy: 12×12, words run right, down or diagonally down. challenge: 15×15, every direction. expert: 18×18, every direction. A longer word grows the grid to fit, up to 20×20. Defaults to easy. |
| seed | integer | – | Grid layout. The same words and seed give the same grid. Leave out for a new layout. |
| title | string | – | Title printed on the sheet, up to 80 characters. Defaults to "Custom Word Search". |
| words | – | yes | The spelling words, 4 to 20, letters only: an array, or one string with the words separated by commas or new lines. |
| Name | Type | Req | Description |
|---|---|---|---|
| directions | string | yes | – |
| grid | array | yes | – |
| level | string | yes | – |
| levelName | string | yes | – |
| pdfUrl | string | yes | – |
| playUrl | string | yes | – |
| seed | integer | yes | – |
| size | integer | yes | – |
| title | string | yes | – |
| words | array | yes | – |
No examples provided.
search_activities Search activities ~137
Search every printable activity by title, topic or a word in the puzzle, like the site's search box. Each query word must start a word in the puzzle ("ant" finds Ants, not Elephant). Narrow by activity or level if you like. Each hit includes the printable PDF and the play URL, plus slugs for get_activity and show_word_search. Puzzle PDFs include an answer key. Game and drawing practice PDFs do not.
| Name | Type | Req | Description |
|---|---|---|---|
| activity | string | – | Only this activity. |
| level | string | – | Only this level. |
| query | string | yes | Topic, title or word, for example "farm" or "space". |
| Name | Type | Req | Description |
|---|---|---|---|
| hits | array | yes | – |
| moreUrl | string | yes | – |
| query | string | yes | – |
| total | integer | yes | – |
No examples provided.
show_word_search Show a word search ~113
Show a word search a child can play in the chat: drag across the letters to find each word, and found words cross off the list. Also returns the grid as text and a link to print the PDF. Pass a seed for a new grid; a slug and seed always give the same grid here, on the site and in the PDF.
| Name | Type | Req | Description |
|---|---|---|---|
| seed | integer | – | Grid layout. Leave out for the site's default grid. |
| slug | string | yes | Word search slug, for example "farm-friends". |
| Name | Type | Req | Description |
|---|---|---|---|
| directions | string | yes | – |
| grid | array | yes | – |
| level | string | yes | – |
| levelName | string | yes | – |
| pdfUrl | string | yes | – |
| playUrl | string | yes | – |
| seed | integer | yes | – |
| size | integer | yes | – |
| slug | string | yes | – |
| title | string | yes | – |
| words | array | yes | – |
No examples provided.
How do I install the Professor Otter MCP server?
Professor Otter is a hosted endpoint at https://professorotter.com/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · professorotter.com
claude mcp add --transport http com-professorotter-activities 'https://professorotter.com/mcp'
What is the Professor Otter MCP server?
Professor Otter is an MCP server listed in the public MCP registry as com.professorotter/activities. Free printable kids activities: word searches, mazes, color by number, sudoku and more. This page covers its hosted endpoint (https://professorotter.com/mcp).
Is the Professor Otter MCP server safe to use?
Professor Otter scores 89 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the Professor Otter MCP server expose?
Professor Otter exposes 6 tools: list_activities, search_activities, get_activity, show_word_search, make_word_search, list_products. Their descriptions and schemas cost roughly 731 tokens of context every time the server is loaded.
Does the Professor Otter MCP server require authentication?
No. We connected to Professor Otter without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the Professor Otter MCP server still maintained?
Professor Otter is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.
What did VerifyMCP test on the Professor Otter MCP server?
VerifyMCP ran 14 checks on Professor Otter, covering TLS certificate, Authorization, HTTPS, HSTS header and 10 more. Supply Chain Security and Provenance & Transparency do not apply to a hosted endpoint, so they were not tested. The score does not measure everything, and the scoring documentation lists what it leaves out.