Open-Source MCP for Kilter Board Logs, With Hard-Won Private-API Lessons

fin_expat · reddit · 2026-09-16

A developer open-sourced kilter-mcp, a read-only MCP server for your Kilter Board climbing logbook. Any MCP-speaking agent (Claude, Cursor, Kiro, Codex) gets nine read-only tools over your own data: sessions, sends, projects, grade pyramid, hardest sends, monthly progression, angle comparison. Run uvx kilter-mcp with two env vars; listed in the official registry as io.github.wmmg101/kilter-mcp.

Hard-won lessons for building against an app's private API:

Kilter uses Keycloak; password grant with in-memory tokens and refresh rotation, no token files. After a rejected login it backs off 60s so a config typo can't trip account-lockout protection
The grade table is a public endpoint, so grades are fetched live with an embedded fallback; log semantics (what a row means, what counts as an "attempt") were the hard part and are documented in the repo
Tool errors flow through the SDK's ToolError, so agents get "credentials not configured, set X and Y" instead of a generic failure. Network-layer output passes a redaction step, and a test walks a failed-login traceback to ensure the password appears in no frame
--check prints a secret-free diagnostic for bug reports

Unofficial, not affiliated with Kilter: github.com/wmmg101/kilter-mcp

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Open-Source MCP for Kilter Board Logs, With Hard-Won Private-API Lessons

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