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

Annotations already declare readOnlyHint and openWorldHint, but the description adds genuinely useful signal beyond them: that data comes from all devices, that it is ordered newest-first, that there is typically a few minutes of propagation delay, and that login is required. The latency and auth prerequisites are exactly the kind of behavioral detail annotations cannot express.

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 one tight sentence with a parenthetical covering scope, ordering, and latency, and the core scope is front-loaded. The only minor inefficiency is that the parenthetical bundles three unrelated facts instead of a cleaner separate clause, but nothing is wasted.

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?

There is no output schema, so the description is the only place an agent could learn what a record contains; it says only 'songs' (曲) without naming fields such as title, artist, or played-at timestamp. Ordering and delay are covered well, but the return shape is left fully undefined for a tool whose whole value is returning a list.

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%: the single limit parameter is already documented with default 10 and max 100. The description adds no extra meaning about the parameter, so the baseline 3 applies.

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 combination (get the currently logged-in user's recently played songs), which is clear on its own. However, it does not distinguish this tool from the close sibling get_listening_history, so an agent has to infer the difference between 'recently played' and 'listening history'.

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 one concrete usage scenario ('can answer "what was I just listening to"'), which implies when to use it. It does not say when not to use it or point to get_listening_history as the alternative for older or more complete history, so routing between two similar tools is left to guesswork.

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