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

Adds meaningful behavioral context beyond annotations by emphasizing that the operation is free, redelivery of the same task_id is free, and specifying authentication methods (Bearer header or agent_key argument). It also gives the equivalent HTTP route. These details are not present in the annotations, which only indicate idempotency and non-read-only, so the description enriches the agent's understanding without contradicting the annotations.

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 fairly concise and front-loaded with the core purpose, but it repeats 'FREE' three times in two consecutive statements, which is redundant and undermines conciseness. The structure otherwise flows from purpose to cost to authentication to route, but the repetition wastes space.

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 tool's simplicity (3 params, no output schema), the description covers the essential aspects: purpose, optional deferral, cost behavior, authentication, and equivalent HTTP route. It does not describe error handling or response output, but with no output schema, return value details are not required. It is complete enough for an agent to select and invoke this tool correctly.

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% coverage with detailed per-parameter descriptions, so the baseline is 3. The tool description reiterates some param info (e.g., agent_key as a header alternative, delay_seconds for deferral) but does not add substantial new meaning beyond the schema descriptions. It effectively mirrors the schema rather than extending it.

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?

Clearly states it 'explicitly return a claimed task to the queue instead of waiting for its visibility timeout, optionally deferring it.' The verb 'return' specifies the action on the resource, and it distinguishes from sibling tools like inbox_ack by framing it as a way to hand work back rather than completing or acknowledging it.

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?

Provides a clear context: use when you want to return a claimed task instead of waiting for its timeout. Also mentions the optional delay for deferring. However, it does not explicitly name alternative tools or state when not to use it, so it falls short of the 'explicit when/when-not/alternatives' standard.

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