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

Annotations declare destructiveHint=true, idempotentHint=true, openWorldHint=true, and readOnlyHint=false. The description adds valuable behavior beyond those: the signing secret is immutable and will not be returned, the call replaces the global event list, and status controls delivery enable/disable. It also instructs the agent to follow llmContext results, which is practical operational guidance. It does not spell out the exact effect of advancedOptions or whether non-mentioned fields are patched, but the schema already documents fields, so a 4 is fair.

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, zero fluff, front-loaded verb+resource, followed by a compact field list and two high-value caveats. The important constraint (secret immutable) and cross-tool instruction (follow llmContext) are included without bloating the text.

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 rich schema, output schema, and annotations, the description covers the top-level concerns: what can change, the runtime mode instruction, and the secret caveat. The only minor omissions are explicit warning that the event list is replaced (though the schema already says full replacement) and any note about advancedOptions applying to the webhooks group — but the description names that group itself. Value-adding behavior is complete enough for selection and invocation.

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% and quite rich: IDs are typed (wh_..., ws_...), environment is pinned by get_me grants, and enabledEvents explicitly means full replacement. The description reinforces the most semantically loaded points (status controls deliveries, advanced options are grouped, secret never changes). It doesn't redefine everything, which is correct given the schema already carries the parameter meaning.

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 states a specific verb ('update') and resource ('webhook endpoint') and enumerates all mutable fields (URL, name, status, event list, advanced options), which clearly distinguishes it from siblings like create_webhook_endpoint, delete_webhook_endpoint, or update_webhook_subscription. It also adds a precise non-negotiable fact: the signing secret never changes. The action and scope are 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?

The description does not explicitly say 'when not to use this tool or alternatives,' but 'Update' plus the full list of supported fields provides clear context that this is the editing endpoint for a webhook endpoint rather than creation/deletion or subscription editing. The final instruction to follow llmContext guidance in results is a useful decision-continuation cue. Absence of an explicit alternative-routing statement is the only gap.

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