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

Annotations already declare readOnly, openWorld, idempotent, non-destructive hints. The description adds meaningful behavioral facts: no API key required, the response is identical to a well-known URL, and the validation workflow. It complements the annotations without contradiction.

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 sentences: a punctuation call that the action is safe without an API key, followed by a clear factual description of what is returned and why it matters. It is front-loaded, efficient, and contains no empty wording.

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-parameter, read-only tool that has an output schema, the description explains the response content and the validation purpose. It might have added a few words on why schema_hash matters, but the picture is essentially complete given the annotation coverage.

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?

zero parameters, and the input schema already states 'No arguments — the owner is derived from the authenticated principal.' The description doesn't add parameter semantics, but the baseline 4 for parameter-less tools is appropriate.

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 it fetches the AgentContractV1 descriptor (version + schema_url + schema_hash) and hosted_runtime facts, and explicitly notes it is identical to /.well-known/agent.json. This is a specific verb-resource-action that distinguishes it from siblings like verify_contract.

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?

Provides explicit usage context: 'No API key is needed', 'call this now', and 'to validate the contract before acting'. It tells the agent when to use it, though it does not mention when not to use it or name alternative tools.

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