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

With no annotations, the description must carry the behavioral burden; it partially does by specifying 'GET /v1/capacity', which signals a read-only query, and by framing it as a pre-decision check that should not itself spend. However, it does not explicitly state side-effect guarantees or how the response is structured, leaving some behavior implicit.

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 a single, front-loaded sentence with no filler: endpoint first, then the data provided, then the usage context. Every part contributes.

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 one-parameter GET endpoint, the description covers the essential purpose, timing, and a hint at return values ('DIEM and price bands'). However, 'DIEM' is left undefined and no return format or error behavior is described, so an agent may still have to infer some details.

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% — the only parameter, max_price_cents, already has a description ('Optional buyer ceiling 30-80'). The tool description does not add further parameter-level meaning, so this is at the baseline of 3.

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 uses the specific verb 'GET' with the resource '/v1/capacity' and states the domain ('DIEM and price bands before funding or spend decisions'), making the core purpose understandable. It distinguishes itself from funding/spend siblings by being the pre-decision capacity lookup, though the unexplained 'DIEM' acronym keeps it from a perfect score.

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?

The phrase 'before funding or spend decisions' provides a clear situational trigger for calling this tool. It does not explicitly name sibling alternatives or state when not to use it, so it falls just short of full guidance.

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