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

Annotations already indicate readOnlyHint=false (write operation) and destructiveHint=false (non-destructive). The description adds the specific mutating actions (rename/recolor) and clarifies it operates on an existing label, which is helpful. However, it does not disclose what happens if both name and color are omitted (e.g., no-op) or any error behavior, but given the annotations cover safety, this is acceptable.

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 two sentences with no wasted words. The primary action is front-loaded, and the alternative tool is mentioned succinctly. Every word earns its place.

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 simple update tool with 4 parameters, no output schema, and annotations covering the safety profile, the description adequately states the purpose, the target, and when not to use it. It does not mention return values or error cases, but those are not expected given the absence of an output schema and the tool's simplicity.

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 input schema provides descriptions for all 4 parameters (100% coverage), including 'New display name' and 'New display color'. The description's phrase 'rename or recolor' adds minimal meaning beyond the schema, so the baseline of 3 applies. It doesn't introduce additional parameter details or clarifications.

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 clearly states the action ('rename or recolor') and the target resource ('an existing label on a standalone project'). It also explicitly distinguishes from the sibling create_standalone_label by naming it, so an agent knows exactly what this tool does without ambiguity.

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 explicit guidance to use create_standalone_label instead when adding a new label, which directly addresses the most likely confusion with a sibling. It does not mention other alternatives like delete or update_status, but for this tool's specific purpose the guidance is sufficient and clear.

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