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

Annotations already cover the safety profile (readOnlyHint=true), and the description adds real value beyond them: it discloses that the return is a synthesized answer rather than raw results, and that the raw provider response is surfaced in _meta. It stops short of noting accuracy/recency caveats or result-count behavior, so not a 5.

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?

Front-loaded with the core capability, then routing, then return shape — a sensible ordering. Slightly chatty in the middle, where "Prefer this before guessing" and "If a specific page is needed..." partially restate the same routing idea, but nothing is wasted enough to be a 3.

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?

For a single-parameter read tool with no output schema, the description covers everything an agent needs: what it does, when to pick it over the sibling, what comes back, and where the raw response lives. No meaningful gap remains.

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?

Schema coverage is 100% and the query parameter description already explains natural-language phrasing, context to include (SDK version, self-hosted vs cloud), and the ~600 character limit. The tool description adds no parameter meaning beyond that, so the baseline 3 applies.

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?

States a specific verb and resource ("Semantic search (RAG) over the Langfuse documentation") and immediately scopes it against the sibling: broader questions vs. a single page served by getLangfuseDocsPage. An agent can choose between the two without opening either schema.

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?

Explicit routing rules: use this for broader questions that a single page cannot answer, and call getLangfuseDocsPage first when a specific page is needed. "Prefer this before guessing" adds an explicit fallback ordering, which is exactly the when-to-use signal agents need.

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