获取视频流地址

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

Beyond the readOnlyHint annotation, it discloses two operationally critical facts: the direct URLs require a `Referer: https://www.bilibili.com/` header and expire in about 2 hours. Both would silently break an agent's downstream download if omitted.

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?

Two sentences, front-loaded with what is returned, then the download caveat and the sibling pointer. Nothing is padded and every clause carries 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?

With no output schema, the description still names the return payload (quality/codec list, selected DASH video and audio URLs, size estimates) and the constraints on using those URLs. An agent has everything needed to call it and act on the result.

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%, with each parameter (page, codec, quality codes, include_all) fully documented in the schema itself, so the baseline is 3. The description only echoes the quality/codec enumeration at a high level and adds no format or default nuance beyond the schema.

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: it lists available qualities/codecs and returns the selected DASH video/audio stream direct URLs with size estimates. This is clearly separable from siblings like bili_video_info (metadata) and bili_download (file saving).

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?

Explicitly routes the agent away from this tool when the goal is saving locally ("想直接存到本地请用 bili_download"), which is the key fork. It does not say when to prefer bili_video_info over this tool, but the main alternative is named.

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