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

Annotations already cover the safety profile with readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable behavioral context: no authentication requirement, hash-verifiable output, and equivalence to /.well-known/agent.json, which informs the agent about expected response semantics beyond the 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 short and front-loads the most actionable fact: no API key needed. The only minor redundancy is repeating the fetch/validate idea, but it remains efficient and scannable for an agent.

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 zero-argument, read-only tool with an output schema and safety annotations, the description is complete. It tells the agent that no auth is needed, what will be fetched, that the output matches a known standard, and how to use the result before taking further action.

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 description covers 100% of the input surface, so there is no parameter meaning left for the tool description to add. The schema's note that the owner is derived from the authenticated principal is sufficient; baseline 4 applies.

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 names a specific verb and resource: it fetches the AgentContractV1 descriptor with version, schema_url, and schema_hash, plus hosted_runtime facts, and explicitly equates it to /.well-known/agent.json. This clearly distinguishes it from siblings like verify_contract by framing it as the fetch step, not the verification action.

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 can be called immediately, and it should be used to validate the platform contract before acting. It does not explicitly name alternatives or when-not-to-use conditions, but for a zero-argument read tool the timing and prerequisite guidance is sufficient.

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