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

Annotations already indicate idempotentHint=true and destructiveHint=false, so the bar for added behavioral context is lower. The description adds value beyond those annotations by explaining the mechanism: it keeps the original idempotency key, causing the client's deduplication to drop the message if the first attempt already arrived. This gives the agent a concrete behavioral consequence not contained in the structured 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 two tight sentences with no filler. The primary action is front-loaded ('Re-queue a past delivery'), and the second sentence delivers the crucial idempotency caveat clearly and memorably.

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 two-parameter tool with no output schema and annotations covering idempotence and destructiveness, this description is largely complete. It explains the key behavioral nuance an agent needs: duplicate deliveries will be dropped if the original idempotency key was already seen. It does not explicitly state what happens when the first attempt did not arrive, but that is reasonably implied and not a critical gap.

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 the baseline is 3. The description does not add meaningful parameter-level detail beyond the schema; it refers to 'a past delivery' but does not, for example, clarify that delivery_id comes from package_list, which the schema already states. Thus the description neither improves nor harms parameter understanding.

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 opens with a specific verb and resource: 'Re-queue a past delivery.' It is clear that this tool replays a previously sent delivery rather than creating or testing one. However, it does not explicitly distinguish itself from siblings like delivery_test or delivery_configure, so it stops short of full sibling differentiation.

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 implies when to use the tool: for a past delivery that needs to be re-queued, with the caveat that original idempotency is preserved. It gives useful context about deduplication behavior but does not explicitly state when not to use it or name alternative tools such as delivery_test or delivery_configure.

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