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

Goes well beyond the annotations: it discloses the blast radius ('every revision'), the immediate irreversibility of the old secret, the downstream failure mode (signature check failures), and the one-time-only return of the new secret. These are exactly the facts an agent needs before invoking a destructiveHint operation.

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?

Three sentences, each carrying a distinct and necessary fact: the action, the irreversible consequence, and the one-time secret return. Front-loaded with the verb and resource, zero 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?

With no output schema, the description correctly compensates by explaining that the response carries the new secret exactly once and that it must be relayed. Combined with the destructive/idempotent annotations, an agent has everything needed to call this safely.

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?

There is a single parameter with 100% schema description coverage, so the schema already documents endpoint_key. The description adds no syntax, format, or lookup guidance for the key, so the baseline 3 applies.

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 precise verb and resource: 'Replace a webhook endpoint's signing secret.' An agent can immediately distinguish this from sibling mutations like save_webhook_endpoint, archive_webhook_endpoint, or test_webhook_endpoint.

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 operational context clear by describing the consequence of calling it (old secret dies instantly, deliveries fail signature checks until the receiver is updated), which effectively tells the agent when this is appropriate. It does not name an alternative tool or state an explicit when-not condition, so it falls short of a 5.

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