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 context beyond annotations: no API key required, hash-verifiable format, and equivalence to /.well-known/agent.json. 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?

Two punchy sentences, front-loaded with the most actionable information ('No API key needed — call this now'). The hash-matching instruction is slightly redundant with the descriptor contents but still earns its place by telling the agent how to use the fetched data.

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 zero parameters, rich annotations, and an output schema, the description covers the operation's purpose, auth requirement, and usage timing. Nothing an agent needs to invoke it correctly 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 has zero parameters and schema description coverage is 100%, so the baseline of 4 applies. The description adds no parameter details, but none are needed for an empty input schema.

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 states the tool fetches a hash-verifiable AgentContractV1 descriptor and hosted_runtime facts, and equates it to /.well-known/agent.json. However, it does not explicitly distinguish itself from the sibling verify_contract, so it stops short of full sibling differentiation.

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 explicitly tells the agent to 'call this now', notes that no API key is needed, and positions the call as a pre-action validation step ('before acting'). It does not name alternatives or exclusions, but the usage context is clear and actionable.

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