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

Annotations already declare readOnlyHint=true and openWorldHint=true, lowering the burden on the description. The description adds useful behavioral context: it supports page_token pagination, sorting, publish-time filtering, and duration filtering. It discloses no destructive behavior because there is none.

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?

The description is a single dense sentence with no filler: it front-loads the core purpose, then gives routing guidance, then enumerates the supported capabilities. Every clause contributes actionable information.

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 7-parameter search tool, the combination is fully adequate: the description explains when to use it, the schema covers all parameter semantics at 100%, an output schema exists, and annotations declare the read-only and open-world behavior. Nothing needed for correct invocation is missing.

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 the schema already thoroughly documents all 7 parameters, including the keyword exclusion rules, page_token invariants, and filter enum meanings. The tool description only summarizes the supported filter dimensions without adding parameter-level meaning beyond what the schema provides, which is the baseline case.

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?

Description opens with a specific verb-resource pair: 'search Bilibili videos' (搜索 Bilibili 视频), and clarifies the exact trigger condition: a user needs to find videos by search term. It also explicitly distinguishes itself from detail/comment lookup tools for existing links or IDs, and from the sibling search tool for articles.

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?

The description explicitly says when to use this tool ('when the user needs to search videos by search term') and when not to ('when already have a video/article/dynamic link or content ID, use the corresponding detail or comment tool'). It names the exclusion category but not specific sibling tool names, which are available in the sibling list.

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