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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered by structured data. The description adds the shape of the payload (URL, events, active state, description), which is modest extra context but not the kind of behavioral detail (error behavior for unknown IDs, permissions) that would raise this higher.

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 tight sentences, the action front-loaded before the return detail, with no filler. The parenthetical enumeration of returned fields is slightly redundant given an output schema exists, costing it a point.

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 one-parameter read tool with read-only annotations and an output schema, the description supplies what an agent needs to invoke it correctly. The only real omission is routing guidance against webhook_list for discovery, which is a minor gap at this complexity level.

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 the single 'id' parameter is documented as 'Webhook ID', so the schema carries the full parameter burden. The description adds only that the ID selects a single subscription, which is baseline-level value; 3 is the correct baseline here.

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 (Get) and resource (webhook subscription) with the access key (by ID), so the agent knows exactly what it retrieves. It does not explicitly distinguish itself from sibling webhook_list (list vs single-by-ID) or webhook_set, but the 'by ID' qualifier makes the distinction inferable.

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?

Usage is implied by the 'by ID' framing – use this when you already know a webhook's identifier – but the description never names webhook_list as the discovery alternative or states when not to use it. No prerequisites or guidance about where IDs come from are given.

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