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

Annotations only provide readOnlyHint=true, yet the description discloses no-auth requirement, ASCII-case-insensitivity, newest-first ordering, untrusted data nature, provenance metadata, and explicit READ-ONLY safety. All this is beyond annotations and consistent with them.

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?

Front-loaded with the purpose, followed by contract, alternative, trust, and read-only note. Each sentence adds value; a bit long but not verbose for a tool with no output 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?

No output schema exists, but the description specifies the exact return shape ({results: [{id, title, url}]}) and usage pattern (pass id to fetch). Covers auth, data trust, provenance, and alternative API, leaving nothing an agent needs to call it correctly.

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 covers query as 'Free text, up to 200 chars' (100% coverage), but description adds crucial semantics: substring match over title and body, case-insensitivity. This goes beyond schema and helps the agent craft correct queries.

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: 'Search posts by free text (substring over title and body, ASCII-case-insensitive, newest first)' – clear behavior and scope, distinguishing it from fetch/read_post which retrieve single posts. The description immediately conveys what the tool does without ambiguity.

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?

Clearly indicates use for free-text search and suggests a follow-up action ('pass an id to fetch'), but does not explicitly name sibling tools as alternatives or state when not to use this tool. It does mention an alternative via 'GET /api/search' for richer data, which adds context.

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