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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds meaningful context: a cost of $0.15 USDC, a single-fetch behavior, and the nature of the returned data (access checks, commerce signals, risk). It does not contradict annotations, but it does not disclose other behavioral details like rate limits or error handling, though the bar is lower given the annotations.

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 concise at two sentences plus an example, and it front-loads the core purpose. The price and example add useful context without bloat. However, the example's inclusion of 'intent' could be considered unnecessary or misleading, slightly degrading the structure.

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 tool with one parameter and no output schema, the description covers core functionality, price, and a usage example. It is reasonably complete but lacks any mention of what the response structure looks like (though no output schema exists) and does not address the relationship to sibling tools. The misleading 'intent' parameter in the example further reduces completeness.

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 0%, and the description does not adequately compensate. The only parameter 'url' is not explicitly explained, though the format 'uri' provides some clarity. The example uses 'intent=research' which is not in the schema, creating confusion about accepted parameters. This is a significant gap for a tool with a single parameter.

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 states that the tool provides 'Single-fetch URL intelligence, access checks, commerce signals, and risk,' which clearly indicates its function. The term 'single-fetch' differentiates it from sibling batch_preflight, and the listed features distinguish it from narrower tools like access_check. However, it lacks an explicit verb such as 'fetches' or 'analyzes,' so it falls short of a fully specific purpose statement.

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?

No explicit guidance is given for when to use this tool versus alternatives. The phrase 'single-fetch' implies it is for one URL at a time, but it does not mention batch_preflight for multiple URLs or premium_preflight for advanced features. The example includes an 'intent' parameter not present in the schema, which may mislead rather than clarify usage.

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