explain_recommendation

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

With no annotations, the description carries the full behavioral burden, and it does disclose the internal mechanics: the mood vector, which of three source layers produced it, the nearest named moods, and the mood last served against. It stops short of stating error behavior (e.g., what happens if the song was never recommended) or confirming it is side-effect-free.

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?

Front-loaded with the core purpose in the first clause, followed by one sentence enumerating what is reported. No filler, no repetition 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?

For a read-only explanatory tool with an output schema present, the description need not restate return formats and is complete enough to call correctly. The only real gap is the undocumented video_id, which is minor given the output schema carries the result contract.

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 0% for the single required video_id, and the description never mentions it, so it adds no meaning beyond the bare property name. The parameter is fairly self-evident, which keeps this from being a 1, but the description does not compensate for the coverage gap.

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 and resource ('Explain why a song was recommended') and scopes it to mood terms. This clearly separates it from the action-oriented siblings like recommend_from_song and recommend_from_playlist, which produce recommendations rather than explain them.

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: call this after a recommendation exists to understand its basis. There is no explicit when-to-use, no statement of prerequisites (e.g., must the song have been recommended?), and no routing to alternatives among the ten siblings.

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