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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds real behavioral context on top: result cap and ordering, the silent-empty failure mode, scope limited to indexed values, and a cost signal ('1 request'). It stops short of auth/rate-limit detail, but that is not needed for a read-only search.

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 tight sentences, front-loaded with the method and result cap, then the failure precondition, then the sibling routing. No filler and nothing repeated from the schema.

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?

An output schema exists, so return-value documentation is unnecessary. Given the four params, full schema coverage, and read-only annotations, the description supplies exactly the missing pieces: scope, cap, precondition, and tag-exclusion routing.

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 'list', 'query', 'includeData' and 'includeItems' are all documented in the schema itself. The description adds no syntax or format guidance beyond the schema (e.g. nothing extra on query length or includeData semantics), 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 (full-text BM25 search over a list's searching indexes) plus the result shape (at most 10, best first). An agent can distinguish it from list_items, get_item, and the index-family siblings without opening any 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?

Explicitly excludes tags and routes that case to the sibling: 'Tags aren't searched: filter by tag with list_items.' It also states the precondition for any results at all ('a list without a searching index always finds nothing'), so the agent knows when this tool is useless.

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