Reference implementation Data compiled from public sources as of 2026-10-26. Not an assessment, certification or recommendation. Confirm current status with the vendor and the issuing body.
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Trace · registry probe · T1 reproducible run

Registry probe of LangChain's discovery endpoints

LangChain · 2026-10-11 · AgentDossier refresh · harness probe-1.0

Scenario. Fetch and validate the ARD manifest, A2A agent card and MCP server card at the publisher's well-known paths

Observed. A2A verified (unsigned); MCP invalid

EntryGET on the publisher's well-known discovery paths
Actionsserved Agent2Agent (A2A) document; served Model Context Protocol (MCP) document
Egressno
Human approval—
Secrets touchedno
Bundlebundles/tr_st_55582a24f05e0d8c_2f64500b · sha256:606bcfc466829a1d486c7684732d2bb1133f7bd9805871f614d3fff215240497 · download (JSON)
Chainsha256:94afd0cc5194f66a6a2c3403583f96878ff234b29cee68aa23f2373626983746
prev sha256:9c5ff6d4d653d0a560f19e7ee0171e888da47e832d1e4166c9572a01d3a4ae9c

Transcript

# Probe transcript — LangChain

Agent `res_55582a24f05e0d8c` · publisher domain `docs.langchain.com` · 2026-10-11 · harness probe-1.0

## Agent2Agent (A2A)

- requested `https://docs.langchain.com/.well-known/agent-card.json`
- result: **verified**
- declared version: 0.3 (card 1.0.0)
- signed: no
- skills advertised: langchain

## Model Context Protocol (MCP)

- requested `https://docs.langchain.com/.well-known/mcp.json`
- result: **invalid**

---
Observation only: the registry fetched public well-known paths and validated the documents against the protocol specifications. No credentials, no message exchange beyond discovery, nothing written.

Produced automatically on every refresh; a new bundle is written only when the observation changes

A trace describes one version on one date. It is evidence of behaviour, never a certification. Dispute it through the agent's dossier; corrections are appended, never overwritten.