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

Annotations already declare readOnly, openWorld, idempotent, and non-destructive behavior. The description adds valuable context beyond that: no API key is required, the descriptor is hash-verifiable, and the payload is identical to the well-known agent.json contract. It does not describe failure modes or edge cases, but given the strong annotations and presence of an output schema, this gap is minor.

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 three compact sentences, front-loaded with the most decision-relevant facts: no API key needed and call now. Each sentence carries distinct information about the resource, its identity, and the intended validation workflow. The slight repetition of 'schema_url' is functional because it shifts from identifying the resource to prescribing how to use it.

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 rich annotations, the description is complete. It explains what is fetched, the fields involved, the authority of the payload, and the intended validation step. The only omission is explicit routing relative to verify_contract, which is a usage nuance rather than a blocker for correct invocation.

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 description has no real parameter burden. The schema already conveys the only relevant semantic: the owner is derived from the authenticated principal. This matches the baseline for a no-parameter tool.

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 clearly specifies a fetch operation on a defined resource: the AgentContractV1 descriptor with version, schema_url, and schema_hash, plus hosted_runtime facts. It also anchors the tool to a known standard ('identical to /.well-known/agent.json'), making the purpose unmistakable. It does not explicitly distinguish the tool from the sibling verify_contract, though the naming and content make the separation inferable.

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: it can be called immediately, requires no API key, and should be used to validate the platform contract before acting. It emphasizes a 'call this now' posture, which is strong guidance for invocation timing. It does not explicitly mention alternatives or when-not-to-use cases, so it stops short of full routing guidance.

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