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

Annotations already declare the mutation profile (readOnlyHint=false, idempotentHint=true, destructiveHint=false), so the bar is lower. The description still adds genuinely non-obvious behavior: webhook blocks begin posting to the newly active revision's URL from their next delivery, and archived endpoints can be reactivated — neither is derivable from the annotations or schema.

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, no redundancy. The core action is front-loaded and the parenthetical clarifies scope economically; the second sentence carries the delivery-timing behavior without padding.

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 two-parameter mutation with full annotation coverage and no output schema, the description supplies what the agent needs to act correctly and predict consequences. The only minor gap is not stating explicitly what happens to the previously active revision (demoted to draft/archived?), though 'rollback' implies it.

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%; both parameters (endpoint_key, revision) are already documented, including the pointer to list_webhook_endpoint_revisions for the revision number. The description adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 ('make an existing webhook endpoint revision the active one') and immediately disambiguates the word 'activate' by enumerating the three scenarios it covers: rollback, draft activation, and unarchiving. The resource name differentiates it from the activate_*_revision siblings (pipeline, gateway_server, escalation_path, team_escalation_policy) without needing to name them.

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?

Gives clear context for when the tool applies (rolling back, promoting a draft, restoring an archived endpoint), which tells the agent what situations call for activation. It stops short of naming alternatives or prerequisites, but the resource-specific name makes the choice among siblings unambiguous.

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