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

Annotations already declare read-only, idempotent, non-destructive, and open-world behavior. The description adds useful context beyond that: no authentication key is required, the response mirrors /.well-known/agent.json, and schema_hash should be verified before relying on the contract. This is meaningful transparency without contradicting 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 two compact sentences with an action-first opening. Every phrase carries information: authentication status, call urgency, exact payload contents, canonical endpoint match, and the validation workflow. No schema or annotation content is redundantly repeated.

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?

Complexity is low with zero parameters, and an output schema exists, so the description does not need to explain return fields. It covers what is fetched, how it relates to the standard agent.json contract, and how to verify it, making the tool fully usable without further investigation.

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 that no arguments are needed and the owner is derived from the authenticated principal. The description appropriately adds no parameter-specific syntax, so the baseline score of 4 for a no-parameter tool is correct.

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 names a specific verb ('fetch') and a precise resource: the AgentContractV1 descriptor with version, schema_url, and schema_hash, plus hosted_runtime facts. The phrase 'identical to /.well-known/agent.json' anchors the resource to a familiar contract, making the tool's purpose unmistakable even without explicit 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?

It gives a clear when-to-use instruction: call now, no API key needed, and use it to validate the platform contract before acting. It does not name alternative tools or explicit exclusion criteria, but none are really needed for a zero-parameter, read-only endpoint.

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