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

Annotations only flag it as a non-idempotent, non-destructive write; the description goes well beyond them by disclosing the delivery format (signed POSTs, Standard Webhooks + CloudEvents), the https transport requirement, pattern-matching behavior for events, that the signing secret is returned, and that a key is required. That is exactly the extra context an agent needs before invoking a webhook-registration write.

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?

One dense, front-loaded sentence that leads with the action and resource, then layers in delivery semantics, event patterns, return value, and auth. No wasted words, and every clause carries operational information.

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?

With no output schema, the description correctly notes that the signing secret is returned, covers auth ('needs a key'), transport (https), and event filtering. It stops short of addressing duplicate-URL behavior or whether a subsequent test_webhook call is expected, which would close the remaining gap for a write tool that is explicitly not idempotent.

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 already 100%, so the baseline is 3. The description adds meaningful semantics beyond the schema by naming concrete event types (feed.item.published, feed.followed, feed.created, submission.approved), restating that feed.* patterns work, and clarifying that omitting events registers all events.

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 ('Add') and resource ('account webhook') and immediately characterizes what the webhook does (signed POSTs with Standard Webhooks + CloudEvents). The verb 'Add' cleanly separates it from the sibling update_webhook, delete_webhook, and list_webhooks 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?

Implies usage context ('Add an account webhook') and mentions an auth prerequisite ('Needs a key'), but never says when to use this versus update_webhook, test_webhook, or rotate_webhook_secret, nor what happens on a duplicate URL. Guidance exists but is inferred rather than explicit.

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