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

readOnlyHint=true and openWorldHint=false already establish that this is a safe, closed-world read, so the description's burden is lighter. It adds genuine value by disclosing what the payload contains (prices in USDC, payment explanation, plans), but says nothing about freshness of the indicative prices, result size, or whether the catalogue is static.

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?

A single dense sentence with the catalogue framing front-loaded and no filler. It reads as a noun-phrase fragment rather than a statement of action, which slightly weakens the opening, but nothing in it is wasted.

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 no parameters, no output schema, and safety covered by annotations, the description carries most of the burden and does explain the return contents well. It stops short of saying anything about how large or fresh that catalogue is, which is the one thing an agent might still need to know.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The 100% schema coverage signal is moot given the empty property set.

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?

A specific resource is named (the Data API catalogue) with its contents spelled out: endpoints, return values, parameters, price per call in USDC, payment mechanics, and plans. It is clearly distinct from siblings like get_guide, list_runs, or get_api_status, though the description never explicitly says so; the verb is carried by the tool name rather than the prose.

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 only implied: an agent can infer this is the discovery tool for the Data API, but the description gives no when-to-use framing and names no alternatives. It does not say, for example, that this should be called before drafting an evaluation request or that a live status tool exists separately.

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