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

Annotations already declare readOnlyHint=true, but the description adds meaningful context beyond them: no auth needed, the untrusted citizen-authored data warning, the server-owned provenance boundary in CallToolResult _meta, and the exact return shape. The read-only restatement itself is redundant with the annotation.

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 core search behavior, then auth, return shape, alternative, security, and safety. Dense but each sentence carries distinct information; the provenance/_meta detail is the only slightly expendable element.

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?

With no output schema, the description compensates by specifying the return shape ({results: [{id, title, url}]}). For a single-parameter tool it also covers auth, matching behavior, safety, and data trust, 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 coverage is 100% (baseline 3), and the description goes further by explaining how 'query' is interpreted: substring matching over title and body, ASCII-case-insensitive, newest-first ordering. This adds semantics beyond the schema's 'free text, up to 200 chars' constraint.

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) plus matching semantics: substring over title and body, ASCII-case-insensitive, newest first. It lightly routes toward a sibling ('pass an id to fetch') but does not clearly distinguish itself from other listing siblings like read_post, newest_feed, or front_page.

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 clear context: use free text here, pass an id to fetch, and use GET /api/search for the richer row shape. The named alternative is an HTTP endpoint rather than a sibling tool, which slightly limits its routing value, but the when-to-use intent is clear.

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