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

Annotations already mark this as read-only, idempotent, and non-destructive, and the description reinforces this by calling it a fetch. It adds genuinely useful behavioral context: no authentication barrier, hash-verifiability, equivalence to a well-known endpoint, and the recommended validation workflow (match schema_hash against schema_url).

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?

Three sentences, each earning its place: the callability/auth status, the resource contents, and the validation action. The key fact ('no API key needed') is front-loaded, and no wording is redundant.

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 zero parameters, an available output schema, and annotations covering safety/idempotency, the description leaves no practical gap. It explains what is returned, how it relates to a known standard, and exactly what the agent should do with the result.

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, so there is nothing for the description to explain at the argument level. The schema already notes that the owner is derived from the authenticated principal, and the description's zero-parameter nature is implicitly confirmed by the tool being directly callable. Baseline 4 is appropriate for a no-param 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 identifies the tool's function: fetching the AgentContractV1 descriptor (version, schema_url, schema_hash) and hosted_runtime facts. It also defines the relation to /.well-known/agent.json, making the resource unmistakable even without inspecting the output schema.

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 provides actionable guidance on when to call it: no API key is needed, it can be called immediately, and it should be used to validate the platform contract before acting. It lacks explicit 'when not to use' or alternative tool comparisons, but the context is clear enough for an agent to decide.

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