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

Annotations already cover the safety profile (readOnly, non-destructive, closed-world), so the description's added value is the variable response shape: normally ids/titles/URLs, but expanded to chapters when matches are few. That conditional behavior is genuinely useful for planning, though the 'few matches' threshold is left undefined.

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 short clauses, front-loaded with the core action and immediately followed by the return shape. No filler; every phrase carries information about either matching or output.

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 one-parameter, read-only tool with no output schema, the description covers purpose, matching mode, and return contents adequately. The only gap is that the conditional 'few matches' branch has no stated threshold, which leaves the agent unable to predict the response shape.

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 0%, so the description must carry the burden, and 'by words as written' meaningfully constrains the query to literal/keyword text rather than semantic search. It does not mention the 1-200 character bound, but the key semantic of the single parameter is conveyed.

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+resource ('Find chapters and sections of the guide') and clarifies the granularity (chapters vs. sections) as well as the matching mode ('by words as written'). It also positions itself relative to `fetch` by saying it returns ids for it, so an agent can tell the two apart.

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?

The workflow is only implied: returning 'ids for `fetch`' suggests search-then-fetch, and 'with few matches it also returns the chapters, to choose from' hints at a browse fallback. Nothing explicitly says when to use this over `index` or `read`, and no exclusions are stated.

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