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

The description enriches the sparse annotations by disclosing the synchronous execution, use of HMAC-SHA256 signature, standard URL safety check, returned fields including an error placeholder, and that test delivery is always on-demand regardless of subscription. This goes far beyond the annotations (readOnlyHint: false, destructiveHint: false) and provides essential behavioral detail.

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?

The description is two sentences, front-loaded with the core action, and every clause adds value: the signature mechanism, the safety check, the return signature, and the subscription behavior. No filler or repetition.

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?

Given the single parameter, no output schema, and sparse annotations, the description fully covers the tool's behavior, return shape, and usage context. It explains the synchronous nature, signature, safety check, and exactly what fields are returned, making it self-contained for an agent.

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?

The input schema already fully documents the only parameter (webhook_id) with a description including the authenticated-account constraint. The tool description adds no extra parameter semantics beyond what the schema provides, so the baseline of 3 is appropriate.

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 clearly states the action: 'Synchronously POST a synthetic webhook.test event to a registered endpoint.' This identifies a specific verb (POST), resource (registered endpoint), and the synthetic event type, distinguishing it from sibling webhook management tools like register_webhook, update_webhook, and delete_webhook.

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?

Provides clear context for when to use: 'Use this to verify your integration before relying on compel.completed / compel.failed events.' It explains the tool's purpose relative to real events and notes it ignores the endpoint's events subscription, indicating it is for on-demand testing. However, it does not explicitly mention alternatives or when not to use, so it stops short of a full 5.

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