ctx.cat MCP

ctxcat-mcp is a local stdio MCP server with a public-only reader and renderer. It accepts bare public share IDs for fetch_ctx and verify_ctx.

Tools

• fetch_ctx: accept { "id": "<public-id>" } and return bounded public content with its verification result.
• share_ctx: retained for compatibility, but intentionally fails before file or network I/O because share creation returns lifecycle capabilities. For a Codex session, run ctxcat share <full-codex-session-id> in a user-controlled terminal. Lower-level file sharing uses ctxcat file share ... --capability-output PATH.
• verify_ctx: accept { "id": "<public-id>" } and return verification without content.
• render_trace: accept exactly one of bounded inline content or a bare public share ID, with an optional display name.

Backend URLs, reader keys, full URLs, and local paths are not accepted as MCP selector or configuration fields. render_trace.content and optional render_trace.name are already model-visible before MCP processing and may contain ordinary bounded trace or display text. Callers must not put reader or lifecycle capabilities in those values and must not rely on MCP to sanitize them. MCP treats the values as render input, not as share selectors or backend configuration. Private and unlisted shares stay outside model-visible MCP; use the CLI or TypeScript client for capability-bearing operations. An unlisted ID is itself a reader capability; MCP cannot undo disclosure once it is given to a model. Native session resume is CLI-only.

Install

Install the public MIT-licensed package bytes with bun add --global @synthlabs/ctx-cat-client@0.3.1; the source repository remains private. The CLI guide verifies both ctxcat and ctxcat-mcp. Direct Git dependency installation is not supported.

Use CTX_CAT_BASE_URL for local or staging backends.