Langfuse: Auth Status

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only declare readOnlyHint=true; the description goes well beyond that. It discloses the cost profile ('one small API call per project, plus two'), the full set of things reported (version, v4 events-only mode with no /traces or /sessions, whether writes are enabled), and that remediation hints are returned when configuration is missing. That is exactly the extra context an agent needs to decide whether to call it and how to interpret the result.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The core purpose and the 'check this first' trigger are front-loaded, and every clause (version, v4 mode, write flag, remediation, API call count) carries distinct information rather than restating the title. It is dense and dash-heavy, which makes it slightly harder to scan than a shorter version would be, but no sentence is waste.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, so the description must describe the return shape, and it does: project names, per-key validation results, version, events-only mode, write-enabled flag, missing-config guidance, and request cost. For a zero-parameter read-only diagnostic tool, an agent has everything needed to call it and interpret the response.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so there is no input semantics to explain and the baseline applies. The description also usefully clarifies that the returned project names are what other tools' `project` argument accepts, which is value beyond this tool's own empty schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Uses a specific verb-plus-resource pair: it lists the Langfuse projects this server can read, validates each key against the project it is filed under, and reports configuration state. An agent immediately knows this is a discovery/diagnostic tool rather than a data-fetching one, and the description explicitly links its output ('the names the other tools' `project` argument takes') to how sibling tools are invoked.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit trigger: 'Keys are project-scoped, so this is the first thing to check when data looks wrong or missing.' That is clear situational guidance an agent can act on. It stops short of naming when not to call it or an alternative, but with no sibling tools there is little left to route between.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.