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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely non-obvious context that survives the update: 'Deliveries keep the same format and signing secret', which tells the agent no consumer-side re-configuration is needed. It omits whether the update is partial or full-replacement semantics, which matters for a 4-field mutation.

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 short sentences, front-loaded with the mutation and its fields, followed by the one behavioral fact that matters. The API reference link is the only extra and is directly useful for edge cases.

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 mutation tool with no output schema and only safety annotations, the description is adequate but thin: it never states patch-vs-replace semantics, permission requirements, or behavior on invalid event names. The core call can be made correctly, but an agent would have to guess at several edge cases.

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 0%, so the description carries the burden and does name three of the four parameters (url, events, active). It does not cover the required 'id' parameter, the allowed event enum values, or whether omitting a field clears or preserves it, leaving meaningful gaps the schema does not fill.

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 names a specific verb and resource ('Change a webhook's...') and enumerates the mutable fields (URL, events, active flag), making it clearly distinct from webhooks_create, webhooks_delete and webhooks_list by name and intent. It stops just short of explicitly routing away from siblings, but the operation is unambiguous.

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?

There is no when-to-use versus when-not-to-use guidance, no prerequisites (e.g., that the webhook must already exist, or which events require which plan), and no cross-reference to sibling tools such as webhooks_create or webhooks_delete. Usage must be inferred entirely from the verb.

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