Jarroba Tools · Logs

@jarroba/mcp-logs

An MCP server that lets your AI read a log it could never fit in its context.

claude mcp add jarroba-logs -- npx -y @jarroba/mcp-logs

// Claude Desktop, Cursor, Cline, VS Code…{ "mcpServers": { "jarroba-logs": { "command": "npx", "args": ["-y", "@jarroba/mcp-logs"] } } }

12 tools · ~5.5k tokens of context · stdio, runs on your machine · nothing is uploaded.

Why this exists

Every log tool for an AI takes pasted text. A production or CI log is tens or hundreds of MB, so pasting is not an option — and the interesting part is never the part you would have pasted.

These tools take a file path. The server runs in Node, so it opens the file itself and hands back only what fits. An agent debugging a red CI run cannot read the log; it can ask questions about it.

The tools

Make your agent use it (Claude Code hook)

An agent with these tools will still Read a 300 MB log out of habit. hooks/big-log-read.mjs is a PreToolUse hook that stops a Read of a big log (by name: *.log, rotated *.log.N[.gz], *.jsonl, anything under logs/; by size: 2 MB, JT_BIG_LOG_BYTES to change it) and tells the agent to call log_analyze / log_reduce with the path instead. Everything else goes through untouched.

{ "hooks": { "PreToolUse": [ { "matcher": "Read", "hooks": [  { "type": "command", "command": "node /path/to/big-log-read.mjs" } ] } ] } }

Two things it will not do

• It will not invent the server's time zone. That is not in the log, and guessing it shifts the entire timeline without anyone noticing. log_profile_suggest says so instead of filling it in.
• It will not tell you how long anything took if the log has no timestamps. It says it cannot.

Privacy, and an honest note

Transport is stdio: your MCP host launches this as a subprocess and talks over stdin/stdout. There is no endpoint, no account and no telemetry. npx downloads the package from npm to your machine the first time; after that nothing goes out.

Two things worth knowing rather than discovering:

• These tools read whatever the process that launched them can read. That is the point — it is how a 200 MB log becomes answerable — so they are exactly as privileged as your MCP host.
• What a tool returns enters your model's context. A log file with hostile text inside it is an indirect prompt-injection channel, the same way a web page is. Nothing here sanitizes that.

Every tool declares MCP annotations: all are readOnlyHint: true, and all are openWorldHint: true because the answer comes from the disk rather than from the arguments.

More

Part of Jarroba Tools — the same engine as the web tools, so the answer is identical. Want everything (90 tools, databases, diagrams, test auditing, SPARQL)? @jarroba/mcp.

MIT — see LICENSE. Source: github.com/Invarato/jarroba-mcp.