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

With no annotations, the description carries the full burden. It discloses return fields and shows via examples that partial updates are supported (e.g., only enabled or only events). However, it does not mention error behavior, idempotency, or prerequisites like authentication, leaving meaningful gaps for a write 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?

The description is well-organized into WHEN TO USE, RETURNS, and EXAMPLE sections, making it scannable. The examples are useful but somewhat verbose; every sentence earns its place, though it could be tightened.

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 is a partial-update operation, and the description covers the main behaviors and return values. However, the empty input schema creates a significant gap that the description only partially fills. It also lacks details on error cases and validation, so it is not fully complete for a real-world agent.

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 input schema has zero properties, so the description is the only source of parameter meaning. The examples clearly show webhook_id being used as an identifier and other fields as optional updates, adding value beyond the empty schema. However, it does not enumerate all possible fields (e.g., description) or state which are required, so a perfect score is not warranted.

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 opens with 'Update an existing webhook subscription,' a specific verb+resource statement that clearly differentiates from siblings like create_webhook, delete_webhook, and list_webhooks. The WHEN TO USE section further narrows the purpose with four concrete use cases.

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 'WHEN TO USE' section provides explicit, concrete scenarios (changing URL, events, enabled status, description) that are actionable. However, it does not explicitly state when not to use the tool or mention alternatives, 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.