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

Beyond the readOnly and idempotent annotations, the description adds valuable behavioral context: no authentication is required, the response mirrors /.well-known/agent.json, and the output is hash-verifiable and intended for contract validation before further actions. This meaningfully informs the agent's expectations and next steps.

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 concise and front-loads the most actionable fact (no API key needed) before specifying the resource. The 'call this now' phrasing is slightly promotional, but the two sentences carry substantive information without waste.

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?

With no parameters, rich annotations, and an output schema present, the description provides all needed operational context: what is fetched, how it relates to a standard endpoint, and what the agent should do with schema_url and schema_hash. Nothing essential 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?

There are zero parameters and schema description coverage is 100%, so the input schema already fully documents that no arguments are needed. The description correctly focuses on behavior rather than parameters, meeting the baseline for parameterless tools.

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 uses the specific verb 'Fetch' and names a concrete resource: the hash-verifiable AgentContractV1 descriptor with version, schema_url, and schema_hash, plus hosted_runtime facts. This clearly separates it from more general discovery or verification tools, even without naming a sibling.

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, and the tool should be called before acting to validate the platform contract. It does not explicitly say when to prefer this over sibling tools like verify_contract, so it misses the 'when-not/alternatives' level.

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