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 safety profile is known. The description adds genuine value beyond that: what a disabled state actually does (stops sending events until re-enabled) and the external precondition that enabling fails if the webhook URL is unreachable. It omits mention of the dry_run path and whether the confirm gate applies symmetrically to enabling.

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?

Three tight sentences with no filler, leading with the action and following with state consequences and the confirmation requirement. Nothing is redundant, though the unreachable-URL caveat is appended after the confirm rule rather than grouped with the enabling path it belongs to.

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 destructive mutation with full annotation coverage and no output schema, the description covers effect, precondition and confirmation flow adequately. The remaining gap is small but real: dry_run is an available escape hatch that the description never surfaces, which an agent could easily miss when deciding how to preview.

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 webhook_id, active, confirm and dry_run are all documented in the schema itself; baseline is 3. The description reinforces the required parameters and the confirm-after-preview contract but adds no syntax, format, or constraint detail beyond what the schema already says, and it never mentions dry_run.

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 pair ('Enable or disable a transactional (Email API) webhook'), and the 'transactional (Email API)' qualifier separates it from the sibling toggle_webhook. It does not explicitly name toggle_webhook or update_transactional_webhook as the non-equivalent alternatives, so sibling differentiation is implied by resource naming rather than spelled out.

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 operational context: pausing requires confirm: true after a preview, and enabling is refused when the URL is unreachable. What's missing is guidance on when to reach for this versus toggle_webhook or update_transactional_webhook, but the workflow for the primary case is unambiguous.

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