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

The bracketed metadata adds real context beyond the annotations: the concrete endpoint path, that the resource must be owned by the authenticated user, and an explicit cost warning ("see your plan — endpoint not in the public credit manifest"), which is why readOnlyHint=false is not contradictory — a credited network call is not side-effect-free. Nothing is said about failure modes such as a non-existent or foreign id, and the group/endpoint lines are largely structural metadata rather than behavior.

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 purpose sentence is front-loaded and the remaining lines are terse, scannable metadata tags with no filler. The cost line is the only slightly odd element, being a plan pointer rather than a number, but it still carries 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?

For a simple 3-parameter read-only lookup, the definition covers scope (owned by authenticated user), the endpoint, the required parameter, and cost awareness, and an output schema already exists so return values need not be described. The only gap is the missing routing versus the list and id_test siblings.

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 the id, fields (compact-mode dotted paths) and precision parameters are already fully documented in the schema, and the description's "[Required: id]" merely restates that. It adds no syntax, format, or compact-mode guidance of its own, so the baseline of 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?

The description states a specific verb and resource ("Fetch a single webhook subscription") and scopes it to the authenticated user, so an agent immediately knows this is an id-based single-resource read rather than a list. It does not name the listing sibling (astroway_webhooks_webhooks) or distinguish itself explicitly from astroway_webhooks_id_test, which is the only reason it falls short of 5.

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?

There is no explicit when-to-use or when-not-to-use guidance and no mention of alternatives such as the webhook list tool or the id_test sibling. Usage is only implied by the word "single", and the only routing hint lives in the schema (the id is "as returned by GET /v1/webhooks"), not the description.

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