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

The description discloses critical behavioral traits beyond annotations: a new key returns a signing_secret exactly once and must be relayed because it cannot be read back; the URL must be public HTTPS. These are essential operational details not present in annotations (which only indicate non-read-only, non-destructive, non-idempotent). This is exactly the kind of context that prevents misuse.

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 concise (three sentences) and front-loaded with the main action. The second sentence about signing_secret is critical but slightly parenthetical in structure. No wasted words, but could be more structured with bullet points or clearer separation of concerns. However, it remains efficient and readable.

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 no output schema and full schema coverage, the description covers the essential return behavior (signing_secret once) and URL requirement. It omits details like what happens on failure, but for a tool with annotations and complete schema, it is nearly complete. The lack of output schema means return values are not fully specified, but the description hints at the response for new keys.

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 provides 100% coverage with detailed descriptions for each parameter, including 'endpoint_key' explaining the key's role in creating vs. revising. The description adds some value by clarifying the activation default and the signing_secret behavior, but most parameter semantics are already in the schema. Baseline 3 is appropriate when schema does the heavy lifting, but the description does reinforce key points.

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 a dual-purpose operation: 'Create a webhook endpoint or save a new revision of one.' It uses specific verbs ('Create', 'save') and the resource ('webhook endpoint'), and mentions activation. It distinguishes from sibling activate_webhook_endpoint_revision by noting that activation is automatic unless overridden. This is precise and identifies the tool's core function without ambiguity.

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 says it activates unless 'activate is false', giving explicit condition for activation. However, it does not mention when to use this tool versus alternatives like activate_webhook_endpoint_revision or rotate_webhook_endpoint_secret. No explicit exclusions or alternatives are named, but the context of creating/saving revisions is clear. Sibling differentiation is implied but not spelled out.

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