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

Annotations only signal readOnly=false and destructive=false. The description adds valuable behavioral detail: `room` remains the playback source while the others join it. This goes beyond what annotations provide and helps predict the operation's effect.

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 tightly written sentences with no filler. The main operation is front-loaded, and the second sentence explains the key behavioral nuance efficiently.

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 low-complexity mutation with 100% parameter coverage and useful annotations, the description is largely sufficient. The only notable gap is the unresolved default-room ambiguity in the schema, which the description does not clarify.

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. The description clarifies that `room` is the anchor and `rooms` are followers, but it does not resolve the schema's internal contradiction where `room` is required yet the property description says 'Omit for the default room.'

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 uses a specific verb ('Group') with a clear resource and outcome: one or more rooms join `room` so they all play the same thing. It also clarifies the directional behavior, distinguishing it from ungroup_room and other sibling tools.

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 clearly conveys when to use the tool: when multiple rooms should play synchronized audio with one anchor room. It does not explicitly name alternatives or exclusions, but the use case is evident.

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