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

Annotations declare readOnlyHint=false, openWorldHint=false, and destructiveHint=false. The description goes beyond this by explaining that a not-found site returns 'found: false', that a successful lookup consumes one site from a monthly allowance (consistent with readOnlyHint=false), and it lists the kinds of data returned (launch date, technologies). This adds meaningful behavioral context.

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 four sentences, each contributing a distinct piece of information: purpose, input hint, failure behavior, and billing note. It is front-loaded with the core purpose and contains no filler.

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 lookup tool with no output schema, the description covers purpose, input, failure handling, billing implications, and a summary of returned data. Annotations cover the safety profile. It could be slightly more explicit about the exact return fields, but it is largely complete.

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%, so the schema already fully documents all four parameters. The description only adds a note that a full URL works for the domain parameter, but does not expand on the other three. Baseline 3 is appropriate when the schema handles parameter semantics.

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?

States a specific verb (lookup) and resource (one site), and distinguishes from sibling tools like find_sites by emphasizing singularity ('one website', 'one site'). The scope is clear enough that an agent can differentiate without checking schemas.

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 when-to-use or when-not guidance. The description gives input format and return behavior, but never mentions alternatives such as find_sites or when to choose this tool over other lookup options. Usage is only implied by the singular resource.

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