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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful behavior beyond that: results carry verdicts, pricing, an official source URL, and a verification date, plus a citation obligation the agent must honor.

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 short sentences, front-loaded with what the tool searches, then what it returns, then the citation requirement. No filler and nothing buried.

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 simple three-parameter lookup with no output schema, the description conveys the source, the return contents, and the attribution requirement. It is close to complete, missing only how many results come back and how category/limit interact with query.

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 only 33%: query has a description and category is a self-describing enum, but limit (1-20) is undocumented in both schema and description. The description says nothing about how query matching works or that category narrows results, so it fails to compensate for the coverage gap.

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: 'Search the Use Which Tool directory of AI tools for builders.' An agent can tell this is a keyword search over a curated directory, though it never explicitly contrasts itself with siblings like get_tool or list_categories.

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?

Usage is implied by the verb 'search' and the target audience ('for builders'), but there is no explicit when-to-use versus when-to-use-a-sibling guidance, and no note that get_tool should follow for full details or that list_categories exists for browsing.

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