music_list

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

Because there are no annotations, the description carries the full burden, and it discloses real operational behavior: the page size of 35 for category browsing, the fact that *_ref references are valid only during this MCP service run, and a safety-relevant warning that has_copyright=false or null must not be used for effects intended for publishing. It omits authentication and permission requirements and does not state whether the operation is read-only, though that is self-evident.

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 front-loaded with the modes, then lists return fields, then follows with the reference-resolution rules. Every sentence carries information, though the reference-resolution paragraph is generic cross-tool plumbing that could live in shared documentation rather than here.

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 must explain the returns, and it does: music_id, title, author, duration_sec, cover_ref, preview_ref, and has_copyright with its usage caveat. The remaining gap is that the description does not say how many results a query search returns or whether results can be paged, but the category case is specified.

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 100%, so the baseline is 3, but the description adds semantics the schema cannot express: the default behavior when both query and category_code are omitted returns the category codes and names, and category_code yields the first page of 35 tracks. That mode interaction is genuinely beyond the field-level descriptions.

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 names a specific verb and resource (list Douyin music) and defines three operating modes: neither parameter (category list), query (keyword search), and category_code (first page of a category). It clearly describes the tool's unique behavior, though it never names the sibling music_apply or explains how this tool differs from it (list versus apply).

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 gives explicit mode-selection guidance: how to call the tool when you want the category list, when you pass query, and when you pass category_code (first page, 35 tracks). The only gap is that it does not say what to do next, such as using music_apply to apply a track, or when to choose search over browsing categories.

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