Langfuse
Use Langfuse evidence to move from a broad symptom to the relevant trace,
observation, session, prompt, or dataset. Start with the narrowest read-only
query that can locate the event, then inspect its concrete inputs, outputs,
timing, and errors.
Route the task
- For trace, observation, exception, latency, or session diagnosis, read
diagnostic and management workflows.
- For installation, credentials, tool groups, output defaults, connection
failures, or empty results, read setup.
- For exact parameters, filters, pagination, output modes, and response shapes,
read the tool reference.
A common investigation starts with fetch_traces(age=60) or
find_exceptions(age=1440, group_by="file"), then fetches the selected trace or
observation by ID. Use full_json_file only when the complete payload is needed;
exports can contain sensitive user data.
Evidence and mutation boundaries
Treat model names, prompts, timestamps, and other values in historical traces
as recorded evidence. Do not rewrite or normalize old model identifiers to a
current name such as gpt-6-astra.
Trace discovery and inspection are read-only. Prompt creation or relabeling,
dataset changes, annotation-queue changes, and deletions mutate Langfuse;
perform them only when the user requested that change.
Prefer read-only server mode for diagnostic work. It disables prompt and
dataset write tools:
langfuse-mcp --read-only
# or LANGFUSE_MCP_READ_ONLY=true
Never commit Langfuse credentials. Keep public key, secret key, and host in
the supported environment or MCP configuration described in the setup
reference. Rotate any exposed key.
Preserve exact IDs and filters in findings so another reader can reproduce
the query. State when pagination, lookback limits, or compact output limits
the conclusion.
1---2name: langfuse3description: Investigate AI traces, observations, exceptions, latency, sessions, prompts, datasets, annotation queues, and scores through Langfuse MCP. Use when the request names Langfuse or asks to diagnose recorded AI behavior.4---56# Langfuse78Use Langfuse evidence to move from a broad symptom to the relevant trace,9observation, session, prompt, or dataset. Start with the narrowest read-only10query that can locate the event, then inspect its concrete inputs, outputs,11timing, and errors.1213## Route the task1415- For trace, observation, exception, latency, or session diagnosis, read16 [diagnostic and management workflows](references/workflows.md).17- For installation, credentials, tool groups, output defaults, connection18 failures, or empty results, read [setup](references/setup.md).19- For exact parameters, filters, pagination, output modes, and response shapes,20 read [the tool reference](references/tool-reference.md).2122A common investigation starts with `fetch_traces(age=60)` or23`find_exceptions(age=1440, group_by="file")`, then fetches the selected trace or24observation by ID. Use `full_json_file` only when the complete payload is needed;25exports can contain sensitive user data.2627## Evidence and mutation boundaries2829- Treat model names, prompts, timestamps, and other values in historical traces30 as recorded evidence. Do not rewrite or normalize old model identifiers to a31 current name such as `gpt-6-astra`.32- Trace discovery and inspection are read-only. Prompt creation or relabeling,33 dataset changes, annotation-queue changes, and deletions mutate Langfuse;34 perform them only when the user requested that change.35- Prefer read-only server mode for diagnostic work. It disables prompt and36 dataset write tools:3738 ```bash39 langfuse-mcp --read-only40 # or LANGFUSE_MCP_READ_ONLY=true41 ```4243- Never commit Langfuse credentials. Keep public key, secret key, and host in44 the supported environment or MCP configuration described in the setup45 reference. Rotate any exposed key.46- Preserve exact IDs and filters in findings so another reader can reproduce47 the query. State when pagination, lookback limits, or compact output limits48 the conclusion.
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