上传永久图片素材

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

With no annotations, the description carries the disclosure burden and does it reasonably well: it states format and size limits per type (bmp/png/jpeg/jpg/gif ≤10MB; thumb jpg ≤64KB) and describes the return values since no output schema exists. Gaps remain around quota limits for permanent materials and failure behavior, but the safety-relevant constraints are surfaced.

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 dense sentence front-loads the action and outputs, then packs per-type constraints compactly. No filler or restatement of the tool name.

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?

Because there is no output schema, the description correctly explains what is returned (media_id, url) and where the media_id can be reused. Parameters and limits are covered; only material-quota and error-handling behavior are unaddressed, which is a minor gap for a two-parameter upload tool.

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 already 100%, but the description adds genuine meaning beyond the schema by attaching distinct format and size constraints to each value of the type enum. The source parameter's accepted schemes are left to the schema, which is acceptable given full coverage.

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 (upload permanent image material to the material library) and names the outputs (media_id, url). The word "永久" implies the permanent-material distinction versus wechat_upload_article_image, but the sibling is never named, so differentiation is inferential rather than explicit.

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 through the note that the returned media_id can serve as a draft cover thumb_media_id, which hints at a real workflow. There is no explicit statement of when to prefer this over wechat_upload_article_image or wechat_create_draft, so the agent must infer the routing.

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