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

The description adds the crucial behavioral trait that only provided fields are changed, which is not captured by the annotations (readOnlyHint=false, idempotentHint=true, destructiveHint=false). This is valuable context beyond the schema. However, it does not mention return values or error conditions, which the annotations do not cover either.

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 a single sentence with no fluff, front-loading the primary action and immediately stating the key behavioral constraint. It is efficiently written and easy to parse.

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 an update tool with 8 parameters and no output schema, the description covers the core behavior (partial update) but omits return value expectations (e.g., whether it returns the updated task or a success message) and error handling for non-existent task_id. While the schema covers parameters, the lack of output information leaves some ambiguity for the agent.

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 has 100% description coverage for all 8 parameters, so the schema already documents each field's purpose. The description adds no parameter-specific details, making the baseline of 3 appropriate.

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 clear verb ('Update') and resource ('an existing task'), distinguishing it from create_task and delete_task. The additional note 'Only provided fields are changed' further clarifies its partial-update nature, which is not evident from the name alone.

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 no explicit guidance on when to use this tool versus alternatives like complete_task (which likely handles status transitions) or other update_* tools. It only implies that it's for updating tasks, leaving the selection to the agent's inference.

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