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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description does add genuinely useful behavioral traits beyond them — constant-time comparison and replay resistance — but leaves open the critical behaviors: what a failed verification returns or raises, whether a timestamp/tolerance window must be supplied, and where the signing secret comes from.

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?

A single dense sentence with no filler, and the two strongest qualifiers (timing-safe, replay-resistant) are front-loaded. It is a fragment rather than a sentence, but nothing is wasted.

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 security-sensitive verification tool with an undeclared, open-ended input object and no output schema, the description should explain the required inputs and the success/failure contract. Neither is present, so an agent knows what the tool is but not how to invoke it correctly.

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 is an empty permissive object (additionalProperties: true) with zero declared properties, so the 100% coverage figure is vacuous — an agent gets no field names. The description names the providers it supports but never identifies the inputs required (raw payload, signature header, secret, timestamp), leaving the caller to guess the contract.

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?

States a specific verb+resource ("webhook signature verification") and enumerates the supported providers (Stripe, GitHub, Slack, Shopify, Twilio, generic HMAC), which no sibling tool covers. It stops short of saying what a successful call produces (valid/invalid verdict vs. error), so it is clear but not fully self-differentiating on outcome.

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?

There is no when-to-use guidance at all: nothing says to call this on inbound webhook receipt, nothing says what to do when verification fails, and no preconditions (e.g. shared secret availability) are mentioned. The provider list hints at applicability but does not route the agent among choices.

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