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

Annotations only declare readOnlyHint=true; the description adds genuine context by mapping the call to the underlying endpoint (GET /v1/project/projection/{projection_id}/schema) and by characterizing the payload as column metadata. It stops short of noting error behavior for an unknown projection_id, so it is not fully exhaustive.

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 short sentences, with the core purpose front-loaded before the API-mapping aside. The endpoint reference is compact and plausibly useful, though it is arguably redundant overhead for an agent that only needs the tool contract.

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 one parameter, no output schema, and readOnlyHint covering safety, the description's brief characterization of the returned columns is close to sufficient. It could say slightly more about the shape of the schema payload, but nothing essential to invocation 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 100% for the single parameter ('The projection's id.'), so the structured field already carries the semantics. The description adds no format or sourcing detail about projection_id beyond what the schema says, keeping it at the baseline.

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 (fetch) and resource (a projection's field schema), and immediately glosses what a schema means here: 'the columns available on its records.' None of the siblings (get_dataset, get_index_job, get_user, etc.) retrieve projection schemas, so the scope is unambiguous.

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?

'one projection' implies this is a single-resource lookup rather than a listing operation, but the description offers no explicit when-to-use guidance, no prerequisites (e.g. that the projection must exist), and names no alternative sibling. Usage is inferable but not stated.

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