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

Annotations already declare destructiveHint=true and idempotentHint=false, so the description's job is to explain what is destroyed or how retries behave. It adds the valuable negative disclosure that the signing secret is untouched and frames the call as a partial patch ("changed fields"), but says nothing about what makes this destructive or how the event list is replaced.

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?

Two sentences, front-loaded with the verb and resource, then the calling convention, then the exclusion. No filler; the only inefficiency is that the parenthetical field list is incomplete relative to the schema.

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?

Output schema and annotations carry much of the load, and schema descriptions cover all parameters. Still missing for a destructive mutation: whether `events` replaces or merges with the existing list, and what the destructiveHint actually entails — the most consequential ambiguity for this tool.

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 the baseline is 3; the description does confirm body is a partial patch at path webhookId. However it enumerates only url and event list and omits enabled and settleMs, which are valid body fields in the schema — a mild mismatch that adds little over structured data.

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+resource ("Update a webhook subscription") and narrows the mutable surface to url/event list, which separates it from create_webhook, delete_webhook and verify_webhook by verb alone. It stops short of naming any sibling explicitly, so 4 rather than 5.

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 signing secret is NOT rotated here" implicitly routes secret rotation elsewhere, which is a useful exclusion. But there is no explicit when-to-use guidance versus create_webhook/delete_webhook/verify_webhook, and no statement of prerequisites such as ownership or scope requirements.

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