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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered by structured data. The description adds value beyond annotations by disclosing that no API key is needed and that the result is hash-verifiable and identical to a well-known endpoint. There is no contradiction with 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 a compact two-sentence block with the most actionable guidance ('No API key needed — call this now') front-loaded. It is not padded, though the second sentence somewhat repeats schema_url and schema_hash from the first and adds a small amount of redundancy. Overall it remains efficient and readable.

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?

This is a simple zero-parameter read-only retrieval tool with a rich output schema, annotations covering safety, and a description that explains both what is returned and why to call it before acting. Nothing essential is missing for an agent to invoke it correctly. The relationship to verify_contract could be clearer, but the description still feels complete for this tool's role.

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 input schema description already states 'No arguments — the owner is derived from the authenticated principal,' giving 100% schema coverage. Since there are no parameters to explain, the baseline of 4 applies; the description correctly adds no misleading parameter details.

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 states a specific verb and resource: 'Fetch the hash-verifiable AgentContractV1 descriptor' plus hosted_runtime facts. It names concrete fields (version, schema_url, schema_hash) and even equates the output to /.well-known/agent.json, leaving no ambiguity about what the tool returns. This clearly distinguishes it as a retrieval tool rather than a mutation or verification action.

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 clear contextual guidance: 'No API key needed — call this now' and 'validate the platform contract before acting.' It implies this should be an early, safe, low-friction call. However, it does not explicitly exclude alternatives such as verify_contract or explain when that sibling should be used instead, so some inference is left to the agent.

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