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

The description discloses the core behavior (fetch and return group counts), implying a read-only operation. However, it does not mention side effects, error handling, or whether the operation is safe, relying entirely on the absence of 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 a single, clear sentence with no unnecessary words or fluff. It is concise and directly states the tool's function.

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?

While the description states the output type (group counts), it lacks details on output format, required parameters for the robots.txt operation, and how the parameters relate to the function. The mismatched parameter descriptions further reduce completeness, leaving the agent without essential context.

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 parameter descriptions are entirely mismatched with the tool's purpose. 'json' is described as 'JSON text to validate' and 'zone' as 'IANA timezone name', both irrelevant to fetching a robots.txt. This misleading information makes the parameters unusable for the described function.

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 action (fetch) and resource (public robots.txt) and the expected output (group counts). It is specific enough to convey the tool's purpose, though it does not explicitly differentiate from sibling tools like normalize-url or validate-json.

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?

There is no guidance on when to use this tool versus the sibling tools. The description does not mention any conditions, prerequisites, or alternatives, leaving the agent without usage context.

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