Community tool: MPP Inspector — CLI debugger for 402 challenges

[amgb20]

Describe the feature

Hi team,

I built an open-source CLI toolkit for inspecting and debugging MPP 402 challenges:

MPP Inspector — https://github.com/amgb20/MPP-Inspector

What it does:

• Parses spec-compliant WWW-Authenticate: Payment headers (id, realm, method, request base64url)
• Decodes the request payload and verifies all fields
• Supports all 6 payment methods (Tempo, Stripe, Lightning, Solana, Card, Custom)
• Discovers endpoints via /.well-known/mpp.json and /llms.txt
• Compares pricing across MPP services
• Dry-runs the full payment flow
• Ships as a Claude Code plugin with MCP tools

It's tested against the live https://mpp.dev/api/ping/paid endpoint and parses challenges correctly (chain 42431, methodDetails, feePayer, etc.).

Also includes a spec-compliant mock server for local development:

npx @mpp-inspector/mock-server
npx mpp-inspector inspect http://localhost:3402/v1/query

Published on npm: https://www.npmjs.com/package/mpp-inspector

Would you be open to:

1. Listing it in the MPP ecosystem/community tools section (if one exists)?
2. Mentioning it in the developer quickstart docs as a debugging companion?
3. Any feedback on spec compliance — happy to align further.

Happy to submit a PR to your docs/README if that's preferred.

Additional context

No response

[brendanjryan]

nice! can you make a pr to be listed here? https://mpp.dev/extensions

[amgb20]

@brendanjryan Hi, I am kinda confused. how do you want me to make the PR?

[brendanjryan]

here is an example: #475

[amgb20]

done @brendanjryan . cheers

[brendanjryan]

ty!