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

The description goes well beyond the annotations by disclosing that the body is resent byte-for-byte, the envelope id is preserved for dedupe, a fresh signature is applied, retries happen, the return is the replay's own delivery record, and other-mode deliveries return 404. This is rich behavioral context with no contradiction to 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 front-loaded with the core action, then efficiently packs the most important behavioral caveats into two sentences. Every clause adds value, and there is no redundant filler.

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 single-parameter tool with 100% schema coverage, the description covers the action, dedupe implications, retries, return value, a key error condition, and scope. It could be slightly more complete by describing the shape of the returned delivery record, since no output schema exists, but this is a minor 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 coverage is 100% because the only parameter, id, is described as 'A delivery id from the log.' The description reinforces that it identifies a delivery but does not provide additional parameter-level format, source, or constraints beyond what the schema already states.

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 precise verb and resource: 'Re-send one delivery to its endpoint', and explains the exact behavior: same body byte for byte, same envelope id, fresh signature, and usual retries. This clearly distinguishes it from sibling tools like list_webhook_deliveries and key-management tools.

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 useful context about dedupe behavior and the 404 condition for 'other mode' deliveries, but it does not explicitly state when to choose this tool over alternatives or how to obtain the delivery id (e.g., via list_webhook_deliveries). The usage context is implied rather than directly instructed.

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