RPN Calculator
REMOTE · APISHED.COM · SCANNED OCT 4
Evaluates Reverse Polish Notation (postfix) expressions: arithmetic, trig, logs, bitwise ops.
Available components
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 Security60
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation not fully verified: no authorisation is required to call this server, and 1 tool(s) never declared a destructiveHint. The MCP spec treats an absent hint as destructive by default, so we cannot call this surface safe. See how to fix → View diagnostics → Unverified
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- HSTS check failed: the Strict-Transport-Security header is absent. See how to fix → View diagnostics → Fail
- DNSSEC is configured correctly; the domain's records validate against the full chain to the root. View diagnostics → Pass
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability80
- AI-judged instruction clarity (excellent).Pass
- Tool/resource definitions use about 120 tokens (~120/item across 1 items; 1 tools + 0 resources), lean.Pass
- 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 Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
- Structured output schemas are declared (100% of tools); any adoption earns full credit.Pass
Tool Safety75
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- 0 of 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation; "rpncalc_eval" implies "eval" and declares no destructiveHint at all, which the MCP spec reads as destructive by default. See how to fix → Fail
- An AI judge read all 1 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.Pass
How do I install the RPN Calculator MCP server?
RPN Calculator is a hosted endpoint at https://apished.com/mcp/v1/rpncalc, 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 · apished.com
claude mcp add --transport http com-apished-rpn-calculator 'https://apished.com/mcp/v1/rpncalc'
{
"mcpServers": {
"com-apished-rpn-calculator": {
"url": "https://apished.com/mcp/v1/rpncalc"
}
}
} {
"servers": {
"com-apished-rpn-calculator": {
"type": "http",
"url": "https://apished.com/mcp/v1/rpncalc"
}
}
} [mcp_servers.com-apished-rpn-calculator] url = "https://apished.com/mcp/v1/rpncalc"
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"com-apished-rpn-calculator": {
"type": "remote",
"url": "https://apished.com/mcp/v1/rpncalc",
"enabled": true
}
}
} openclaw mcp add com-apished-rpn-calculator --url 'https://apished.com/mcp/v1/rpncalc' --transport streamable-http
mcp_servers:
com-apished-rpn-calculator:
url: "https://apished.com/mcp/v1/rpncalc" {
"McpServers": {
"com-apished-rpn-calculator": {
"Transport": "http",
"Url": "https://apished.com/mcp/v1/rpncalc"
}
}
} assistant mcp add com-apished-rpn-calculator -t streamable-http -u 'https://apished.com/mcp/v1/rpncalc'
{
"mcpServers": {
"com-apished-rpn-calculator": {
"type": "http",
"url": "https://apished.com/mcp/v1/rpncalc"
}
}
} The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.
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.
- 4 Oct 26 +1
- Stability: 0.97 → pass security
- 3 Oct 26 −1
- Stability: pass → 0.97 functional
- 28 Sept 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 25 Sept 26 0
- We updated how we score, so this day's move reflects our rubric, not a change to the server See what changed → functional
- 17 Sept 26 +1
- Stability: 0.97 → pass security
- 14 Sept 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 87 to 90. That category is still filling its 30-day observation window: 26 days of observed history at the previous scan, 27 at this one. The score rises as the window fills, whether or not the server changes.
- 12 Sept 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.
- 10 Sept 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.
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 Oct 2026 · Probed https://apished.com/mcp/v1/rpncalc
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=apished.com | CN=YR2,O=Let's Encrypt,C=US | 17 Aug 2026 | 15 Nov 2026 | RSA 4096 | SHA256-RSA | 5f4dfa5fcafb280b9204690908ddbca6b5c |
| SANs: apished.com | ||||||
| CN=YR2,O=Let's Encrypt,C=US (CA) | CN=Root YR,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | RSA 2048 | SHA256-RSA | 4ebd24947e24d394802d84a52fd5b319 |
| 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 secure
Validation of apished.com. — Secure
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| com. | present | 19718 | 13 | Verified |
| apished.com. | present | 38629 | 8 | Verified |
| apished.com. | Verified address RRset verified with the apex keys |
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 |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://apished.com/mcp/v1/rpncalc | Verified | 200 | |
| http (plaintext) | http://apished.com/mcp/v1/rpncalc | HTTPS enforced | 301 | https://apished.com/mcp/v1/rpncalc |
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 →
rpncalc_eval ~120
Evaluates a Reverse Polish Notation (postfix) expression: whitespace-separated tokens, each a number or an operator/function that pops its operands off a stack and pushes the result. Supports arithmetic, exponentiation/modulo, roots, trigonometry, logarithms, rounding, bitwise ops, and constants (pi, e, phi). Always returns the decimal result — for hex/bin/oct rendering, convert the returned number yourself.
| Name | Type | Req | Description |
|---|---|---|---|
| expr | string | yes | space-separated RPN expression, e.g. "3 4 + 2 *" |
Structured output declared, but exposes no named fields.
No examples provided.
What is the RPN Calculator MCP server?
RPN Calculator is an MCP server listed in the public MCP registry as com.apished/rpn-calculator. Evaluates Reverse Polish Notation (postfix) expressions: arithmetic, trig, logs, bitwise ops. This page covers its hosted endpoint (https://apished.com/mcp/v1/rpncalc).
Is the RPN Calculator MCP server safe to use?
RPN Calculator scores 79 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 RPN Calculator MCP server expose?
RPN Calculator exposes 1 tool: rpncalc_eval. Their descriptions and schemas cost roughly 120 tokens of context every time the server is loaded.
Does the RPN Calculator MCP server require authentication?
No. We connected to RPN Calculator without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the RPN Calculator MCP server still maintained?
RPN Calculator is still listed as active in the MCP registry. We last reached this channel on 4 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.