Verify Webhook Signature

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

The annotations already declare readOnlyHint=true, and the description adds valuable behavioral context: 'No network call' clarifies that verification is purely local, and 'uses the per-webhook signing secret you pass in' specifies the authentication mechanism. This goes beyond the annotation by detailing the operational behavior without contradicting it.

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 concise sentences with no fluff. It front-loads the main purpose and immediately adds the critical constraint ('No network call') and the secret context. Every word contributes to understanding the tool.

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?

The tool has five parameters and no output schema, but the description covers the essential behavior: verification method, local execution, and secret usage. It doesn't explicitly state the return value (e.g., boolean) or error handling, which would be ideal, but the simple nature of the tool and strong schema/annotation support make this 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?

The schema covers all parameters (100% coverage), so the baseline is 3. The description adds meaning beyond the schema by explaining the HMAC-SHA256 computation over 'timestamp.body', which helps understand how the signature_header and payload parameters relate. It also clarifies that the webhook_signing_secret is used locally, reinforcing the schema's note that it is NOT the API secret key.

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 clearly states the tool's purpose: locally verifying a PayMongo webhook's 'Paymongo-Signature' header using HMAC-SHA256. It is specific with a verb ('verify'), a resource ('PayMongo webhook signature'), and distinctive details (local, no network call). This clearly distinguishes it from sibling tools that create or manage webhooks.

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 provides clear context: when to use it (to verify a webhook signature) and key constraints (local, no network call, uses the per-webhook signing secret). While it doesn't explicitly name alternatives or exclusions, the context is sufficient given that no sibling tool performs signature verification.

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