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

Annotations already indicate idempotent and non-destructive, but the description adds critical billing details (300 micro-dollar credits per successful call, new requestId is a new billable operation) and the need for credits and auth header. This goes well beyond annotations and is essential for correct usage.

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?

Four sentences with no redundancy. The main purpose is front-loaded, followed by billing and prerequisites. Every sentence adds value; the structure is logical and easy to parse.

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 paid tool with an output schema, the description covers purpose, cost, prerequisites, and recovery. It tells the agent everything needed to call it correctly, including how to avoid extra charges by reusing requestId. No critical information 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 67% (requestId and maxPriceMicroUsd have descriptions, input does not). The description adds context about requestId reuse and billing but does not clarify the input object beyond what the schema shows. Since the schema covers most parameters, a baseline of 3 is appropriate.

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 clearly states the verb 'extract' and the resource 'up to 200 links' plus the resolution of destinations against a URL. It distinguishes the tool from siblings like html_images or html_feeds by its specific function.

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 prerequisites (use agent_utilities_prepare first, requires credits and Authorization header) and explains recovery behavior. It does not explicitly state when not to use this tool or name alternatives, but the purpose is distinct enough that an agent can infer appropriate usage.

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