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

Annotations already mark the tool as read-only, idempotent, and non-destructive. The description adds the meaningful behavioral guarantee of 'No payment or budget debit' and notes the catalog includes authentication and payment availability, which helps an agent avoid expecting a paid or side-effecting operation.

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 no filler; the catalog contents are front-loaded and the clarifying no-debit statement is placed after the main payload. Every clause adds 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 no-parameter catalog lookup with no output schema, the description adequately lists what will be returned (API metadata, inputs/outputs, example, auth, payment availability) and the non-side-effect nature. It does not state the exact response format, but that is not critical for a zero-input introspection tool.

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 the input schema fully describes the call shape and the description adds no parameter burden. Baseline 4 applies because there is nothing for the description to explain about inputs.

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 a specific verb ('Discover') and identifies the resource (cost, latency, and quality analysis APIs) plus the exact metadata returned (inputs, outputs, example, authentication, payment availability). 'No payment or budget debit' clearly separates this catalog/introspection tool from the purchase_* siblings.

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 description gives clear context: use this tool to explore available analysis APIs and their metadata, not to perform actions. 'No payment or budget debit' functions as an exclusion, but it does not explicitly name alternative tools such as purchase_changes or get_free_sample.

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