canimcp
Which MCP clients support what, how each claim is known, and research notes on the parts a support matrix cannot express.
A capability here carries evidence, and evidence carries a tier and the protocol revision it applies to.
| Tier | Means |
|---|---|
declared |
The client says so, in initialize.capabilities or a curated list |
verified |
A probe or conformance scenario exercised it |
observed |
Telemetry over real traffic |
read |
Someone read the client's source at a pinned commit |
Tiers are not ranked. Several can sit on one capability and disagree, and a disagreement is a finding. 2026-07-28 is stateless with per-request _meta, and every revision through 2025-11-25 uses the initialize handshake, so a result on one says nothing about the other.
When to use this
- Before relying on an MCP feature in a server, check which clients implement it and at which protocol revision.
- To find out what a client does with a tool result: which of
contentandstructuredContentreaches the model. - To see where a client's declared capabilities, its source and its observed traffic disagree.
Every page has a Markdown version at the same URL with .md appended, and the same URL returns Markdown for Accept: text/markdown. The registry is JSON under /data, and /llms.txt indexes all of it.
Clients
| Client | Vendor | Category | Prefers | Last read |
|---|---|---|---|---|
| goose | Block | agent-framework | 2026-07-28 |
2026-08-23 |
| Codex CLI | OpenAI | cli | 2025-06-18 |
2026-08-24 |
| opencode | Anomaly | cli | 2025-11-25 |
2026-08-24 |
| Cline | Cline Bot Inc. | ide | 2025-11-25 |
2026-08-25 |
| fast-agent | Shaun Smith (llmindset) | agent-framework | 2026-07-28 |
2026-08-25 |
| OpenClaw | OpenClaw Foundation | agent-framework | 2025-11-25 |
2026-08-26 |
| Hermes Agent | Nous Research | cli | 2025-11-25 |
2026-11-09 |
| Kilo Code | Kilo Code | ide | 2025-11-25 |
2026-11-10 |
| Google Antigravity | ide | 2026-07-28 |
Across clients
- Tool result handling, verified: what reached the model when each client called a fixture tool, from 17 clients run through the probe.
- Capabilities observed in traffic: which capabilities clients declare in real traffic, by protocol revision.
- Research notes: 38 notes on behaviour a matrix cannot express.
Data and schemas
/data/clients.json: the registry. One entry per client is at/data/clients/<id>.json, listed in/data/clients/index.json./data/spec-versions.json: the lifecycle of each capability across protocol revisions./data/verified/<client>.json: the probe's records per client./data/observed/hf-mcp-clients.json: the telemetry feed./schemas/client-registry.json,research-note.json,verified-evidence.json,observed-evidence.json: JSON Schemas, served at their$id.
The source is at https://github.com/olaservo/canimcp. About covers where the data comes from and how to report a correction.