telemetry-mcp

telemetry-mcp is a small, read-only Model Context Protocol server that exposes a configurable metrics/telemetry backend as typed tools: list sources, describe a source's schema, run a bounded query, and compute a single aggregate. It turns ad-hoc "go read the numbers" scripts into constrained, structured tools an agent can call.

The package also ships an opt-in, write-side sibling entrypoint, telemetry-emit-mcp, for at-will OpenTelemetry emission. It is separate from the default query server so telemetry-mcp stays read-only and zero-dependency by default.

The server is catalog-driven by design: it contains no built-in dataset, table, or metric names. Runtime configuration maps public handles to an explicit allowlist of BigQuery tables, time columns, filters, projections, and aggregate columns.

Repo structure: this ships as a per-server repo, following the shipped convention (e.g. reddit-mcp, dispatch-mcp). Whether the fleet's MCP servers consolidate into a single agent-mcp repo is pending a consolidation decision; until that lands, this stays per-server.

Tools

Related MCP server: mcp-bauplan

At-will emit server

telemetry-emit-mcp is a separate MCP server for agents that need to record a value or occurrence while they work without managing OpenTelemetry context by hand. It exports vendor-neutral OTLP using the standard OpenTelemetry SDK and honors the OTEL_EXPORTER_OTLP_* environment variables the runtime already uses.

This routing follows the public otel-emit-at-will skill:

• values are metrics;

• occurrences are events;

• spans are only for bounded operations that can be auto-parented.

The default read-only query server does not import the OpenTelemetry SDK. Install the write-side server explicitly:

pipx install "telemetry-mcp[emit] @ git+https://github.com/selamy-labs/telemetry-mcp@v0.2.0"

MCP client config for the emit server:

{
  "mcpServers": {
    "telemetry-emit": {
      "command": "uvx",
      "args": [
        "--from",
        "git+https://github.com/selamy-labs/telemetry-mcp@v0.2.0#egg=telemetry-mcp[emit]",
        "telemetry-emit-mcp"
      ],
      "env": {
        "OTEL_EXPORTER_OTLP_ENDPOINT": "https://otel-collector.example.internal",
        "OTEL_SERVICE_NAME": "nash-agent"
      }
    }
  }
}

start / end are ISO-8601 instants. filters is an optional column -> value mapping (keys are validated; values are bound as query parameters by the backend, never string-interpolated). limit is capped by the core.

Security model

This server is built so that exposing it does not expose arbitrary data access or command execution. The properties below are enforced in code and covered by tests.

• Read-only. The tools are list/describe/query/summary. There is no write, no DDL, and no run_sql / raw-query escape hatch — a caller cannot supply query text. The optional telemetry-emit-mcp entrypoint is a separate write-side server and does not register any query tools.

• Bounded. Every query is time-ranged and limit-capped (MAX_LIMIT), so a call cannot pull an unbounded result set.

• No embedded credentials. Nothing in this package stores a token or key. Credentials are resolved at call time by an injected CredentialProvider (backed by WIF/GSM/env in production) and handed to the backend per request; they never live in source, in the service, or in a returned payload (tests assert the sentinel credential never appears in output).

• Validated handles. Source / metric / filter-key names are restricted to a conservative identifier shape, so a rejected lookup cannot smuggle injection or path traversal into the backend (defence in depth; the backend's own allowlist is the real gate).

• Catalogued identifiers. Project, dataset, table, time, projection, filter, and metric identifiers must pass conservative validation and come from the runtime catalog. Caller-controlled values are query parameters.

• Scan-capped. Every BigQuery job sets maximum_bytes_billed and disables legacy SQL. Row queries fetch at most limit + 1 rows to report truncation.

Deliberate omissions

• No tool lets the caller supply or override executed query text.

• No tool returns or accepts credentials.

• No mutation/DDL capability — if you need to change data, that is out of scope here by design.

Configuration (environment, resolved at call time)

No credentials are read from the environment by this server; identity is resolved per call from the runtime (WIF/GSM) by the credential provider.

BigQuery catalog

The adapter discovers nothing from INFORMATION_SCHEMA; only entries in TELEMETRY_BQ_CATALOG are visible. Each source declares its physical table, mandatory time column, projected schema, and permitted equality filters. Each metric maps a public handle to one source column:

{
  "sources": {
    "ci.runs": {
      "table": "ci_runs",
      "time_column": "started_at",
      "description": "CI runner job executions.",
      "schema": {
        "started_at": "TIMESTAMP",
        "repo": "STRING",
        "duration_ms": "INT64"
      },
      "filters": ["repo"]
    }
  },
  "metrics": {
    "ci.runs.duration_ms": {"source": "ci.runs", "column": "duration_ms"}
  }
}

Deployment still owns the dataset and a keyless runtime identity with read-only BigQuery access. The adapter creates a client with the credentials resolved for each call and stores neither clients nor credentials.

The write-side telemetry-emit-mcp needs the runtime's OTLP configuration instead: OTEL_EXPORTER_OTLP_ENDPOINT, optional OTLP headers/protocol variables, and OTEL_SERVICE_NAME.

Install

Run the tagged release directly from GitHub with both required extras:

uvx --from "git+https://github.com/selamy-labs/telemetry-mcp@v0.3.0#egg=telemetry-mcp[mcp,bigquery]" telemetry-mcp

Or with pipx:

pipx install "telemetry-mcp[mcp,bigquery] @ git+https://github.com/selamy-labs/telemetry-mcp@v0.3.0"

MCP client config

{
  "mcpServers": {
    "telemetry": {
      "command": "uvx",
      "args": [
        "--from",
        "git+https://github.com/selamy-labs/telemetry-mcp@v0.3.0#egg=telemetry-mcp[mcp,bigquery]",
        "telemetry-mcp"
      ],
      "env": {
        "TELEMETRY_BQ_PROJECT": "speedforge-prod-499002",
        "TELEMETRY_BQ_DATASET": "telemetry",
        "TELEMETRY_BQ_CATALOG": "{\"sources\":{...},\"metrics\":{...}}",
        "TELEMETRY_BQ_MAXIMUM_BYTES_BILLED": "100000000"
      }
    }
  }
}

Architecture

The metrics logic lives once in telemetry_mcp.core.MetricsService; the MCP server in telemetry_mcp.mcp_server is a thin wrapper that serialises structured results to JSON and maps expected failures to ToolError. All data access goes through an injected backend (telemetry_mcp.backend.MetricsBackend) and all credential resolution through an injected CredentialProvider, so the full validate / route / shape path is exercised offline in tests with a fake in-memory backend — no GCP, no network. The default backend (BigQueryBackend) lazily imports its optional client dependency, so the core package has zero runtime dependencies; the mcp SDK and google-cloud-bigquery are optional extras.

See the System Context for the runtime boundaries of the query and emit servers.

Development

python -m pip install -e ".[test]"
ruff format --check .
ruff check .
vulture src tests --min-confidence 80
coverage run -m pytest
coverage report --fail-under=95

License

MIT — see LICENSE.