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

Beyond the annotations, the description adds substantial behavioral context: it is free, requires no API key or account, is deterministic, fetches nothing, touches no third party, and returns a real structuredContent rather than a mock. It also specifies the exact canned inputs and that they come from the host's own data. These details go well beyond what readOnlyHint and idempotentHint already provide.

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 overly verbose and repetitive: 'no third party is touched', 'canned from this host's own data', and 'shape of an answer' are each stated multiple times. While the opening JSON-RPC example is useful, the same information could be delivered in about half the length. The redundancy makes it harder to parse quickly.

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 parameterless example tool with an output schema, this description is complete: it explains exactly how to invoke it, what the input is, what the return value represents, that it is safe and deterministic, and how to use the result. There is no missing information an agent would need to call it correctly.

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 has zero parameters, and the input schema already documents this with an empty object example. The description reinforces that it takes no arguments, which is sufficient baseline for a parameterless tool. No further parameter explanation is needed.

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 a specific action: run this server's own worked example of lint_robots_txt and return the exact structuredContent a real call produces. It distinguishes the example tool from the actual sibling tools by emphasizing it uses canned host data rather than user input. The tool's role as a demo is unambiguous.

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 explicitly tells the agent when to use it: 'Use it to see the shape of an answer before you decide what to send.' It also clarifies that no user data or URLs are involved, which prevents misuse. However, it does not explicitly name sibling alternatives or state when not to use this tool, so it stops short of full when/when-not guidance.

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