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

Annotations provide readOnly/destructive hints, while the description adds context beyond them: the returned receipt's cryptographic content, two verification paths, the no-auth verification endpoint, and the current-signing-key endpoint. It does not detail side effects despite destructiveHint=true, but it adds substantial behavior beyond the annotation set.

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 most important behavior is front-loaded in the first sentence, followed by verification mechanics and the key endpoint. It is dense but not padded, though the final trust-ladder sentence is somewhat illustrative rather than strictly necessary.

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 tool with no output schema and two parameters, the description covers the run behavior, the receipt format, verification methods, and a key retrieval endpoint. The only notable omission is an explicit response shape, but an agent has enough to select and invoke the tool 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?

Schema coverage is 100%, so the baseline is 3, but the description enriches the scenario parameter by linking its shape to sim_scenario, noting defaults apply, and explaining that summary:true certifies the summarized form because the result hash covers the returned result.

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 opens with a specific verb and resource: 'Run a seeded scenario and get back the result PLUS a signed run receipt', and then defines what the receipt is (an Ed25519 certificate over model id, scenario, result hash, service revision). This clearly separates it from scenario-running siblings like sim_scenario.

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 explains how the receipt can be verified and calls reproducibility 'the bottom rung of the trust ladder receipts build', which implies a use case but never explicitly states when to choose this tool over sim_scenario or other sim_* siblings. No when-not or alternative-selection guidance is given.

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