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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so the description is only responsible for input-contract behavior — and it delivers the non-obvious parts: a 1–14 club range, unique-name requirement, and a strict 'upstream rejects any other key' validator warning. It says nothing about cost, latency, or how the analysis is performed, which keeps it out of 5.

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 the core purpose front-loaded, then requirements, then the strict-validation warning. No filler, though the 'only these three' phrasing mildly duplicates the schema's additionalProperties: false and could have been folded into the previous sentence.

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?

An output schema exists, so return values need no explanation, and the remaining risk surface for this single-array-parameter tool — item shape, cardinality, uniqueness, unknown-key rejection — is fully covered. Nothing an agent needs to construct a valid call is missing.

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 0% at the top level, so the description must carry the parameter burden — and it does: it states that 'name' and 'carry_distance_yards' are required, 'loft_degrees' is optional, and that only these three keys survive the upstream validator. The cardinality (1–14) and name-uniqueness rules appear nowhere in the JSON schema and are the kind of detail that prevents failed calls.

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 names a specific verb ('Analyse') and resource ('carry-distance gaps' for golf clubs), so an agent knows this is an analytical tool over a supplied club list rather than an audit/search utility. It stops short of 5 because 'gaps' is never unpacked — what dimension of gap is computed stays implicit and only becomes clear from the output schema.

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?

'Pass 1 to 14 clubs with unique names' gives input constraints but never states when an agent should reach for this tool versus not calling it at all. With an entirely unrelated sibling set there is no routing risk, yet the description still leaves the use case implied rather than stated.

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