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

With no annotations, the description carries full burden and rises to the occasion. It discloses that preserve_headers defaults to true, how resign_with re-signs the payload, the signature header behavior (e.g., Stripe-Signature), and that the tool returns 'response status, latency and body'. This offers substantial behavioral context beyond the schema.

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 tight four sentences: purpose, one default behavior, one conditional behavior, and the return value. Each sentence earns its place with no filler, and the most important information is front-loaded.

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 has 7 parameters, no output schema, and no annotations, the description covers the essential use case, the tricky signing flow, and the return format. It doesn't explain headers/body overrides in prose, but the schema handles those. For a test-runner tool, this is reasonably complete.

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%, so baseline is 3. The description adds meaningful context on top: it explains the default for preserve_headers, the purpose and usage of resign_with, and gives an example of a signature header. This moves it above baseline, though not every parameter (body, headers) receives narrative treatment.

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 'Re-send a captured event to any URL' — a specific verb+object pair — and grounds it as 'the test runner for a handler you just wrote'. This clearly distinguishes it from sibling tools like get_event or forward_bucket.

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?

It states the primary use case ('test runner for a handler you just wrote') and provides conditional guidance for using resign_with ('If you changed the body or the receiver verifies with a different secret'). While it doesn't explicitly name alternatives like forward_bucket, the context is sufficient for an agent to know when to select this tool.

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