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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's job is to add content-level expectations. It does so by listing the included sections (status rule, how to read it, worked example, credits), which tells the agent what it gets back in the absence of an output schema.

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?

Two sentences, no filler. The core purpose is stated first and the usage hint is placed last, so the agent gets the what and the when in a minimal, well-ordered package.

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?

With no parameters, no output schema, and annotations already declaring the read-only profile, the description supplies exactly the missing piece: a preview of the document's contents and the point at which to fetch it relative to run_skill_matrix.

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 nothing for the description to disambiguate; baseline 4 applies. No parameter discussion is needed or missing.

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 ('Explains') and a specific resource (Langereis's skill-matrix gap analysis), and enumerates what the explainer contains (status rule, reading instructions, worked example, credits). It names run_skill_matrix as the sibling it complements, though it doesn't distinguish itself from get_essay or about_niels.

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 condition: 'Use before run_skill_matrix if the user wants to understand the method first.' That routes the agent cleanly in that scenario, but offers no guidance for other cases (e.g., when to read the method vs. just run the matrix outright).

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