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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered by structured data. The description adds non-obvious context: it accepts share text as well as bare links, spans three content types, and clarifies that video copy is not a transcript. It stops short of describing returning fields or pagination, but with an output schema present that gap is minor.

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?

A single compact sentence that leads with the action and resource, then appends the routing alternative and the transcription caveat. Nothing is wasted, though the three densely packed clauses push slightly past ideal front-loading.

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 an output schema present, the description needn't explain return values, and annotations cover the safety profile. Purpose, the sibling fork, and the output caveat are all present, leaving nothing an agent needs to call this 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 description coverage is 100% and the single url parameter is already documented with supported path patterns and an explicit 'don't pass a bare ID' warning. The description's phrase '链接或分享文案' merely echoes that schema text, so baseline 3 is appropriate for a one-param tool where the schema does the heavy lifting.

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?

Names a specific verb (读取/read detail) plus the resource types it covers (文章、视频、微头条) via link or share text. It explicitly distinguishes itself from the sibling toutiao_get_post_detail_by_post_id, so an agent can route without opening either 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?

States the exact condition under which the sibling applies ('只有内容 ID 时使用 toutiao_get_post_detail_by_post_id'), which is the primary routing decision for this tool. It also warns that video descriptions are not speech transcriptions, heading off a likely misuse.

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