ChatGPT Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory Prompt/verify-x402-delivery
How to: ChatGPT Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory verify-x402-delivery
Add Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory to ChatGPT
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Open Settings → Connectors → Advanced → Developer mode and merge this in. Keep any servers already there.
https://assay.agentdiet.dev/mcp-
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Save the file and restart ChatGPT.
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verify-x402-delivery is surfaced in the connector's menu once the server is linked. Unlike a tool, you invoke it deliberately — ChatGPT will not call it for you.
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If it does not appear, check that Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory is connected and that you are looking at its prompts rather than its tools.
Custom connectors are a paid-plan feature and take a remote URL only. ChatGPT cannot run a packaged server locally. ChatGPT docs
Same prompt, other clients
Read from the server itself, by connecting to it and calling prompts/list on 19 October 2026.
A listing does not declare its prompts, so asking is the only way to know them, and this
is what the server actually offers rather than what its listing claims. Names only are
stored; connect the server for each prompt's arguments.