Search the local page index

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description still adds real context beyond them — the FTS5 backend, CJK bigram matching, and the fact that it issues no network requests. It does not cover ranking, result ordering, or pagination behavior.

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?

Three sentences, front-loaded with what the tool is, then usage, then return values and cost. Every sentence carries information; only the closing 'costs no network requests at all' slightly restates the earlier 'local/on this machine' framing.

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 read-only search tool with full schema coverage and annotations covering the safety profile, the description supplies the remaining essentials: what corpus is searched, when to use it, and what it returns (cached URLs, titles, highlighted snippets). No output schema is needed given that the return shape is described.

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 description coverage is 100%, so the schema already documents query, format, and max_results in detail, including the default and bounds. The description only reinforces the CJK bigram behavior, adding marginal meaning over the schema — 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+resource+scope: full-text search over pages already fetched on this machine, backed by a local SQLite FTS5 index. It implicitly separates itself from the web_search/fetch_url family by stressing locality and zero network cost, but it never differentiates from the sibling 'local_index', which is a plausible source of confusion.

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 three concrete situations to reach for it: recalling something read earlier in the session, avoiding a re-fetch, and working offline. There is no explicit when-not or named alternative (e.g. 'for new content use web_search'), so routing is clear but not fully resolved.

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