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

Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds substantial context beyond those annotations: it is deterministic, touches no third party, makes no outbound request, returns exactly the real structuredContent (not a mock), and even lists the specific defects wired into the fixture. This is rich, accurate behavioral disclosure with no contradiction.

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 information-dense but repetitive. 'Touches no third party' appears three times, and 'no arguments' / 'no URL of yours is fetched' / 'input is canned' are stated multiple times in slightly different forms. The front-loaded opening is strong, but the redundancy prevents a higher score.

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?

Despite having no output schema, the description fully explains what the tool returns, how to call it, its side-effect profile, and its purpose. An agent has everything needed to invoke it correctly and interpret the result as a real structuredContent response.

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 schema coverage is 100%, so the baseline is 4. The description reinforces this by saying 'Takes no arguments' and showing an example call with arguments={}. There is nothing more to add.

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 verb ('runs'), a resource ('this server's worked example'), and the exact operation (score_card on a built-in fixture). It is immediately distinguishable from sibling tools like score_card or whoami because it emphasizes that it exercises the server's own end-to-end example with a canned fixture.

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 gives clear context for why this is useful. It does not explicitly name alternative tools or state when not to use it, but the intended usage is well conveyed.

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