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

Annotations provide idempotentHint and destructiveHint, but the description adds critical operational detail: the signing secret is returned only once and must be stored before the reply is discarded, and there is a hard cap of 3 active endpoints. It also clarifies the 'odds moved' trigger precisely and notes the information is not betting advice. This goes well beyond annotations without contradicting them.

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 a single, dense sentence that packs purpose, event list, trigger definition, secret handling, and endpoint limit. It is front-loaded with the action and scope. While long, every clause adds value and there is no filler. Slightly less concise than ideal but still well structured.

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 registration tool with no output schema, the description covers the essential operational facts: what it does, what events are available, the one-time secret, and the account limit. It does not detail authentication or the exact request format, but those are typically handled by the schema or external docs. Overall, it is sufficiently complete for an agent to call 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?

Schema coverage is 100%, so both parameters (url and events) are already documented in the schema. The description does not add extra meaning beyond what the schema provides; it merely reiterates the event types in narrative form. Baseline of 3 is appropriate since the schema carries the semantic load.

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 action ('Register an https endpoint') and the resource (webhooks), enumerates the specific event types with a precise definition of 'odds moved'. It is immediately distinguishable from sibling tools like delete_webhook_endpoint and list_webhook_endpoints by its unique verb and subject.

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 implies the use case (setting up a new webhook endpoint) and even states an operational limit (at most 3 active endpoints), but it does not explicitly contrast with alternatives or state when to prefer delete_webhook_endpoint or list_webhook_endpoints. The guidance is adequate but not explicit.

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