Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add cyanheads/open-meteo-mcp-server --skill field-testgit clone --depth 1 https://github.com/cyanheads/open-meteo-mcp-serverWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/cyanheads/open-meteo-mcp-server/field-test)<a href="https://agentmods.dev/skills/cyanheads/open-meteo-mcp-server/field-test"><img src="https://agentmods.dev/badge/skills/cyanheads/open-meteo-mcp-server/field-test/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/cyanheads/open-meteo-mcp-server/field-test"><img src="https://agentmods.dev/badge/skills/cyanheads/open-meteo-mcp-server/field-test.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00093 | $0.09103 |
| Opus 5 | $0.00046 | $0.04551 |
| Sonnet 5 | $0.00019 | $0.01821 |
| Haiku 4.5 | $0.00009 | $0.00910 |
Grade B, and why
field-test scanned grade B with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured today.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Sends data to an external URLmediumData exfiltration
A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.
stats=$(curl -sS -o "$resp_file" -w '%{http_code} %{time_total}' -X POST "$url" "${headers[@]}" -d "$body") Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
Exercise tools, resources, and prompts against a live HTTP server via MCP JSON-RPC over curl. Starts the server, surfaces the catalog, runs real and adversarial inputs, measures every call (bytes, token estimate, wall-cl This is a copy
100% identical to field-test — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 512 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context
Unit tests (add-test skill) verify handler logic with mocked context. Field testing exercises the real HTTP transport with real JSON-RPC: starts the server, calls initialize, surfaces the catalog, runs inputs, and checks what a client actually sees. It catches what unit tests miss — awkward input shapes, unhelpful errors, missing format output, drift between structuredContent and content[], edge-case surprises.
Actively call the tools. Don't read code and guess.
Transport coverage
This skill drives an HTTP server because curl + JSON-RPC is the most reliable harness for shell-based agents. The same handlers run on both transports — only the framing differs — so HTTP exercises the full functional surface. Both HTTP session modes are covered: a durable Mcp-Session-Id session, and the sessionless initialization a MCP_SESSION_MODE=stateless server performs.
Stdio coverage is a boot check only — run this before Step 1. Run bun run rebuild && bun run start:stdio, confirm the startup logs look clean (banner, expected tool/resource counts, no errors/warnings, no missing-config gripes), then kill it. Pino logs go to stderr in stdio mode (stdout is reserved for JSON-RPC), so they print straight to the terminal when you run interactively. No need to call tools over stdio — the HTTP pass already covered handler behavior.
Steps
1. Start the server
Generate a 10-character alphanumeric ID (e.g. 9DJ73-K103L) and write the helper to /tmp/<project-name>-field-test-<ID>.sh. Use that exact path in every subsequent Bash call. Two agents in the same project tree must pick different IDs — that's what keeps their helper files, server logs, and call scratch from colliding.
The helper itself is stateless — every function takes the IDs it needs (server pid, url, port, MCP sid, server log path) as positional args. mcp_start prints them; the agent threads them through every later call. No env vars, no shared state files.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- today Changed · +119 lines · +17 tokens per session scan A → B 370664dc34d6
- 10d ago First seen · 393 lines · 76 tokens per session scan A 5e0878fedc2a
field-test is a skill published in the GitHub repository cyanheads/open-meteo-mcp-server (5 stars, last pushed today), licensed Apache-2.0. It adds 93 tokens to every session and 9,103 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, makes network calls). It is 100% identical to field-test, differing in 0 lines, and is treated as a copy.
Other skills, from other repositories
api-testing
Testing patterns for MCP tool/resource handlers using createMockContext and Vitest. Covers mock context options, handler testing, McpError assertions, format testing, Vitest config setup, and test isolation conventions.
add-test
Scaffold a test file for an existing tool, resource, or service. Use when the user asks to add tests, improve coverage, or when a definition exists without a matching test file.
api-testing
Testing patterns for MCP tool/resource handlers using createMockContext and Vitest. Covers mock context options, handler testing, McpError assertions, format testing, Vitest config setup, and test isolation conventions.
field-test
Exercise tools, resources, and prompts against a live HTTP server via MCP JSON-RPC over curl. Starts the server, surfaces the catalog, runs real and adversarial inputs, and produces a tight report with concrete findings and numbered follow-up options. Use after adding or modifying definitions, or when the user asks to…
add-test
Scaffold a test file for an existing tool, resource, or service. Use when the user asks to add tests, improve coverage, or when a definition exists without a matching test file.
api-testing
Testing patterns for MCP tool/resource handlers using createMockContext and Vitest. Covers mock context options, handler testing, McpError assertions, format testing, Vitest config setup, and test isolation conventions.