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

Annotations only provide readOnlyHint=false, so the description carries the behavioral burden. It clearly discloses the destructive clear behavior ('clear to delete rows'), notes the performance difference, and adds functional specifics like Chinese substring and English word full-text support. This is strong coverage, though it does not mention irreversibility or permission requirements.

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 dense sentences carry the core message: what the tool accesses, when to use it, and how the main query modes map to parameters. No filler, and the most important guidance is front-loaded.

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 9-parameter tool with no output schema and read-write behavior, the description provides a strong operational overview and covers the main modes. Remaining parameter details (limit, since_hours, kind) are documented in the schema, so the description is sufficiently complete for selection and invocation.

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%, so baseline is 3. The description adds genuine semantic value by mapping modes to parameters: query for full-text search, get for full cached content, stats for counts, clear for deletion. This goes beyond the individual schema descriptions.

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: 'Query the LOCAL CACHE of every page this server has fetched and every search it has run.' This clearly distinguishes it from siblings like fetch and search, making the tool's scope immediately obvious.

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?

Explicitly instructs the agent to 'Check here BEFORE re-fetching or re-searching' and contrasts the instant/free cache hit with a costly fresh fetch. This directly routes usage away from fetch/search when a cached result may already exist.

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