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

Annotations already declare idempotentHint=true, destructiveHint=false, and readOnlyHint=false. The description adds the partial update behavior ('only the fields you want to change'), which is useful beyond annotations. However, it does not elaborate on authorization needs, response behavior, or side effects, leaving some gaps.

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 concise sentences with no fluff. All information is front-loaded and necessary. Every word adds value.

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 high schema coverage and presence of an output schema, the description is mostly complete. It explains the core usage pattern. However, it could be enhanced by noting that the promotion must exist (implied by 'update existing'), or referencing idempotency.

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%, so baseline is 3. The description adds value by clarifying that only changed fields need to be passed, which goes beyond the schema's per-parameter descriptions. This explicitly supports the partial update paradigm.

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 explicitly states 'Update an existing promotion' with a clear verb and resource. This distinguishes it from sibling tools like create_promotion, get_promotion, and delete_promotion, leaving no ambiguity about the tool's function.

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 a concrete usage hint: 'Pass only the fields you want to change,' which communicates the partial update pattern. However, it does not explicitly specify when to use this tool over alternatives (e.g., validate_promotion or create_promotion), nor does it mention prerequisites or when not to use it.

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