get_playback_state

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

Beyond the readOnlyHint annotation, the description discloses the key edge case: when no device is active, the tool returns active=false with nothing else populated, and explicitly states this is normal, not an error. This prevents an agent from misinterpreting a successful response as failure.

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?

Two focused sentences with no filler. The core purpose is front-loaded, and the important edge-case behavior is stated efficiently in the second sentence.

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 parameters, a readOnlyHint annotation, an output schema, and a description that covers both the normal response contents and the no-active-device edge case, nothing needed for correct invocation is missing.

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 tool has zero parameters, so there is nothing for the description to add beyond the schema. The baseline of 4 applies because no parameter documentation is needed.

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 ('Current Spotify playback state') and enumerates the exact fields returned (what's playing, device, progress, shuffle/repeat). This clearly distinguishes it from the sibling tools, none of which target live playback state.

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 provides clear context that this is for the current playback state, implying use when live, real-time state is needed versus historical tools like get_recently_played. It does not explicitly name alternatives or exclusions, but the 'Current' qualifier is enough to guide selection.

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