get_song_url

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It notes that high-quality audio may require VIP permission, which is useful. However, it does not disclose error behavior, rate limits, or authentication needs. The return format is mentioned, but additional operational details are missing.

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 well-structured with Args and Returns sections, each fact earning its place. It is concise, uses bullet points for enum values, and avoids unnecessary prose. The inclusion of the default in both schema and description is a minor redundancy but does not detract from overall clarity.

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?

Given the tool's simplicity (two params, one with enum) and the presence of an output schema, the description is fairly complete. It covers parameter meanings, the VIP caveat, and return format. It does not explain why a single-song URL would be preferred over batch retrieval, but that is not critical for basic usage.

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?

The description adds substantial meaning beyond the schema by explaining each quality enum value (e.g., m4a: AAC, 128: 128kbps MP3) and clarifying song_mid as the song's MID identifier. While the schema already lists enums and defaults, the description enriches the semantic understanding, compensating for the 0% schema 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?

The description clearly states the verb '获取' (get) and resource '单首歌曲的播放链接' (single song's playback link), distinguishing it from siblings like get_batch_song_urls (batch) and get_song_quality (quality info). It is specific and leaves no ambiguity about what the tool does.

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?

No guidance is provided on when to use this tool versus alternatives. The description does not mention compatibility with other functions, prerequisites, or exclusion criteria. While the single-song scope is implied, there is no explicit when-to-use or when-not-to-use guidance.

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