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

Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=true, so the agent knows the mutation/idempotency profile. The description adds useful context that delivery is via HTTP POST, but does not disclose what a re-registration does to an existing webhook or whether the URL must be reachable/verified.

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 front-loaded sentence with no filler, stating the action, the target, and the resulting behavior efficiently.

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 3-parameter mutation with no output schema, the description covers the core behavior but omits re-registration semantics and any preconditions. Annotations carry the safety profile, so the definition is minimally viable rather than fully complete.

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 description coverage is 100%, so url, name, and agent_id are already documented in the schema. The description adds no format, constraint, or syntax detail beyond what the schema provides, making the baseline 3 correct.

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 (register), resource (webhook URL), and the effect (broker delivers incoming messages via HTTP POST), which is concrete and actionable. It does not explicitly contrast with siblings like unregister_webhook or list_webhooks, but the operation is unmistakable.

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 explains what happens after registration but gives no guidance on when to use this versus alternatives such as list_webhooks or unregister_webhook, nor any prerequisites (e.g., whether the agent must already exist, or whether an existing webhook gets replaced).

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