forgesight-mcp

MCP instrumentation for ForgeSight. Turns every Model Context Protocol tools/call / tools/list / prompts/get / resources/read into a correctly-mapped span — with W3C trace propagation across the transport, so a pr-reviewer → github-mcp → internal-api-mcp chain is one trace.

pip install forgesight-mcp

# client side — an agent calling an MCP server
import forgesight
from forgesight_mcp import instrument_mcp_client
from mcp import ClientSession

forgesight.configure()

async with ClientSession(read, write) as session:
    instrument_mcp_client(session)          # one line; wraps the transport
    await session.initialize()
    result = await session.call_tool("get_diff", {"pr": 42})   # execute_tool get_diff

# server side — a tool/resource server
import forgesight
from forgesight_mcp import instrument_mcp_server
from mcp.server import Server

forgesight.configure()
server = Server("github-mcp")
instrument_mcp_server(server)               # extracts traceparent, opens child spans

What you get

• One span per request, mapped per the OTel MCP conventions. A tools/call is the single span carrying both mcp.method.name = tools/call and gen_ai.operation.name = execute_tool / gen_ai.tool.name — never double-instrumented.
• Uniform tool telemetry. A tool reached via MCP and the same tool reached natively both land under gen_ai.tool.name, so "failure rate of get_diff" is one query across both.
• Traces stitch automatically. The client injects traceparent into the request _meta; the server extracts it and opens its span as a child of the caller's — same trace_id.
• Metrics for free. Each call feeds mcp.client.operation.duration and the derived forgesight.mcp.invocations_total (server / method / tool / status).
• Secure by default (P7). tools/call arguments and results are captured only when capture_content resolves true; the redaction interceptor still runs.

Idempotent + reversible

instrument_mcp_client / instrument_mcp_server are idempotent (re-instrumenting is a no-op) and reversible (uninstrument_mcp_client / uninstrument_mcp_server restore the originals). Auto-instrument new sessions/servers at configure() via the install() entry point:

# forgesight.yaml
integrations:
  mcp:
    enabled: true
    auto_instrument: true
    capture_content: false    # P7 default

License

Apache-2.0