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

The annotations already establish read-only, idempotent, open-world, and non-destructive behavior. The description adds useful context beyond those annotations: no API key is required, the response is identical to /.well-known/agent.json, and the output is hash-verifiable. It does not contradict the annotations and enriches the agent's understanding of how the result can be trusted.

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 compact and front-loaded with the most important operational fact: no API key needed. The third sentence is slightly redundant because schema_url and schema_hash were already listed in the descriptor, but the overall length is appropriate and each line contributes actionable guidance.

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 with a rich output schema and strong annotations, the description is complete. It states what is fetched, how it maps to /.well-known/agent.json, and what the agent should do with the returned schema_hash, leaving no missing operational prerequisite.

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 takes zero parameters, so the 0-param baseline of 4 applies. The schema already states 'No arguments', and the description reinforces that the owner is derived from the authenticated principal, so no additional parameter meaning is needed.

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 ('hash-verifiable AgentContractV1 descriptor') plus hosted_runtime facts, and explicitly lists the fields returned (version, schema_url, schema_hash). It also ties the tool to a clear real-world contract: identical to /.well-known/agent.json, which distinguishes it from general-purpose tools.

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 gives a clear usage context: 'No API key needed — call this now' and instructs to validate the platform contract before acting. However, it does not explicitly mention when not to use this tool or name alternatives such as verify_contract, so it stops short of full switching guidance.

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