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

With readOnlyHint already conveying safety, the description adds real behavioral value by enumerating failure modes such as wrong secret, whitespace, re-serialized JSON body, expired timestamp, and wrong URL for Twilio. It stops short of describing the exact return/result format, but the diagnostic scope is well disclosed.

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 one efficient sentence with a front-loaded action and diagnostic scope, followed by a compact provider list. Every phrase adds useful information and there is no repetition of schema content.

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 multi-provider tool with no output schema, the description covers provider scope and common failure causes well. It does not explicitly state per-provider required inputs like timestamp for Slack or URL for Twilio, and the exact return shape is left implied, but the schema fills in some of those details.

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?

At 67% schema coverage, the schema documents most parameter meanings. The description goes further by linking failure causes to parameters (secret, raw_body, timestamp, url), which helps the agent understand how the inputs interact during verification rather than just their types.

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 uses a specific verb and resource ('Check whether a webhook signature is valid for a raw body and a secret') and clearly scopes providers. It also distinguishes the tool from siblings like sign_webhook_payload by emphasizing validation and failure diagnosis rather than generation.

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 makes the tool's context clear (validating webhook signatures across several providers) but never explicitly names alternatives or states when not to use it. An agent can infer usage, but the guidance is implied rather than explicit.

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