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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds useful context beyond those: no API key is required, the payload is hash-verifiable, and the returned data matches a known standard endpoint. This is valuable behavioral disclosure for auth and validation expectations.

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 two sentences with no filler. The most actionable signal ('No API key needed — call this now') is front-loaded, followed by precise return-value facts and a validation purpose. Every sentence earns its place.

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?

Given the output schema exists and the tool has zero parameters, the description covers the essential facts: what is returned, that it matches a known endpoint, and why to call it. It could be slightly more complete by contrasting with the sibling verify_contract, but nothing critical is missing for invoking this tool safely.

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?

There are zero parameters, so the baseline is 4. The input schema already explains that owner is derived from the authenticated principal, and the description further clarifies that no key or arguments are needed. No additional parameter meaning is required.

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 ('Fetch') and a concrete resource: the hash-verifiable AgentContractV1 descriptor with explicit fields (version, schema_url, schema_hash) plus hosted_runtime facts. It further disambiguates by saying it is identical to /.well-known/agent.json, making the tool's purpose unmistakable.

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 clearly says to call this now, that no API key is needed, and that it should be used to validate the platform contract before acting. It gives clear context but does not explicitly name alternatives or exclusions, so it stops short of full when-to-use versus when-not-to-use guidance.

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