"A Python server using FastAPI to expose public web API endpoints to an agent" matching MCP connectors:

Workflow planning, recovery checkpoints, coordination, fixtures, and compatibility tools for agents.

Prompt evals over MCP: run a prompt on your dataset, score each output 1-5 with an LLM judge.

Test-inbox API for email and SMS: create inboxes, long-poll messages, extract OTPs and links.

Free platform to test MCP clients without installing anything. Create mock tools with dynamic templates, configurable delays, conditions (if/then), and response sequences. Supports JSON-RPC 2.0 over Streamable HTTP. Built-in text_echo and json_echo tools. Rate-limited tiers: anonymous (5 calls/min, 1 mock tool), registered (10 calls/min, 4 mock tools), premium (60 calls/min, unlimited). Zero setup — no install, no registration required. More info: https://www.testmcp.dev

Check that your AI is being logical. Free tool that mathematically catches contradictions in agent reasoning. No account needed. Also offers paid guardrails that converts natural language to formal verification proofs, that anyone can check succinctly.

Read-only, deterministic AI triage and readiness tools implementing Sophon's published rubrics.

Deterministic validation for AI-generated artifacts: JSON Schema, OpenAPI response, SQL syntax.

Check if your MCP server is ready to publish on the MCP Registry, Smithery, or npm.

Hire a real human for real-world verification, product testing, AI output review, and errands.

Deterministic recipe verification engine — validates AI-generated recipes against master SOPs.

Grade MCP servers A to F with the open behavioral litmus. npm: full toolset; hosted: lookups only.

Promotion gate for AI agents: leakage audits, exact-statistics verdicts, and a live report card.

Email compatibility analysis across 15 clients — preview, audit, fix, diff, deliverability.

Verifies web animation vs WCAG 2.2.2/2.3.3: validated specs, deterministic reduced-motion-safe CSS.

Runs your code against a contract; returns HELD or BROKE at the exact input. Deterministic.

Test the voice agents you run: scored transcripts, pass/fail verdicts, latency and WER metrics.

Generate realistic relational test data — 156 field types, 22 locales, JSON/CSV/SQL, free previews.

Read-only MCP server for the OPERANT AI operating-agent calibration benchmark.

Machine-readable taxonomy of 100+ AI system failure modes spanning factuality, alignment, planning, code generation, and instruction following.

MCP server for the Fail Modes taxonomy — a knowledge base of AI system failure modes