canimcp: which clients silently break your MCP server's tools

Description and use

canimcp detects silent client failures in MCP tool lists, enabling early CI detection.

Problem

Clients silently drop or truncate MCP tools without reporting errors, causing missing or incomplete tool lists.

Outcome

canimcp identifies silent tool failures across MCP clients, enabling early detection in CI pipelines.

Workflow

• 1. Point canimcp at a saved tools/list response or server command.
• 2. Run canimcp specifying the client (e.g., codex).
• 3. canimcp analyzes the response, compares against expected schema, and reports findings with evidence grades.
• 4. Review findings to identify silent failures or truncations.
• 5. Adjust schema or client configuration based on findings before full testing.

Evidence

I wanted that list as a check I could run in CI, so I built canimcp: point it at a saved tools/list response or at your server command, and it reports which client+version breaks on what, each finding carrying its evidence grade and a source link.

Source

A tool argument named ids[]? Claude Code drops the tool silently. A 14 KB input schema? Codex compacts it and loses your required nested fields. 2049 tools on one server? Codex keeps the first 2048.

Source

What it is not: a live test. It sees the schema, not runtime result shapes or tonight's client build. For real client trials there is M3; canimcp is the fast pass in CI before that.

Source