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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior. The description adds useful behavioral details beyond annotations: no API key required, response is identical to /.well-known/agent.json, and the data is hash-verifiable for contract validation. No contradiction with 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 front-loaded with the key call-to-action and includes the essential information, but it contains redundancy: 'Fetch schema_url and match schema_hash' repeats fields already listed earlier, and the emoji/call-now style adds noise without new semantic content. Could be tightened.

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 no-argument read-only tool with an output schema present, the description provides enough context: what is returned, how to use it for validation, and the auth requirement (none). The equivalence to /.well-known/agent.json further disambiguates the returned payload. Nothing critical is missing.

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 takes zero parameters, and the input schema itself explains that the owner is derived from the authenticated principal. The description does not need to add parameter semantics; per the calibration baseline for 0-parameter tools, this is sufficient.

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 states a specific verb (fetch), a specific resource (AgentContractV1 descriptor), and lists the exact fields returned (version, schema_url, schema_hash, hosted_runtime facts), plus the equivalence to /.well-known/agent.json. This makes the tool's purpose clear, though it does not explicitly differentiate from the sibling verify_contract tool.

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 gives clear usage context: no API key is needed, it should be called before acting, and the returned schema_hash should be matched to validate the platform contract. It does not explicitly mention alternatives or exclusions, but the instruction to call it early is actionable.

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