play

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

No annotations are provided, so the description carries full responsibility. It mentions 'start or resume' but does not disclose behavioral details such as whether it replaces the current queue, what happens if no device is specified, or side effects on existing playback state. It also does not explain the difference between using uris vs context_uri, which is behaviorally significant. This is a thin description for a state-mutating action.

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 only two sentences, front-loaded with the core action, and contains no superfluous words. It is concise and to the point.

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 complexity (5 optional parameters, no output schema, no annotations), the description is inadequate. It does not explain typical use cases, the distinction between uris and context_uri, when to resume vs start fresh, or what errors might occur. It also fails to distinguish itself from play_from_search, leaving the agent uncertain about tool selection.

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 schema documents all parameters with descriptions. The description adds minimal extra meaning beyond 'optionally target specific content', which does not clarify parameter interactions or selection criteria. Baseline 3 is appropriate since the schema does the heavy lifting.

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 states a specific action ('Start or resume playback') and resource ('playback'), and mentions optional targeting of content. It is distinct from siblings like play_from_search, though it doesn't explicitly name that sibling. The purpose is clear but could be more precise about the distinction.

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 implies a general playback control tool, with optional content targeting. It does not explicitly state when to use this instead of play_from_search or other siblings, nor any prerequisites or exclusions. The context is clear but lacks direct guidance on alternative selection.

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