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

Annotations already cover readOnly, idempotent, openWorld, and non-destructive behavior. The description adds useful context: no API key is needed, the descriptor is hash-verifiable, and the result is identical to /.well-known/agent.json. This meaningfully extends the agent's understanding beyond the 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?

The description is short and front-loaded with the most actionable fact ('No API key needed — call this now'). The content is efficient, though the phrase 'call this now' is slightly promotional and 'Fetch' is repeated; still, every sentence contributes useful information.

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 discovery tool with an output schema and clear annotations, the description covers what is returned, why it can be called immediately, how it relates to the standard .well-known endpoint, and how to use it for contract validation. Nothing essential is missing 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?

The tool has zero parameters and the schema already states 'No arguments — the owner is derived from the authenticated principal.' With 100% schema description coverage and no params, the description carries no additional parameter burden. 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 states the tool fetches a hash-verifiable AgentContractV1 descriptor (version + schema_url + schema_hash) and hosted_runtime facts, matching /.well-known/agent.json. The verb and resource are specific, and the tool's role is unambiguous. It could be stronger by explicitly contrasting with verify_contract, but the purpose is not vague.

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 says 'No API key needed — call this now' and instructs to fetch schema_url and match schema_hash before acting, giving clear when-to-use context. It does not explicitly mention when not to use this tool or name alternatives like verify_contract, 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.