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

Annotations already cover read-only, idempotent, non-destructive, and open-world behavior, so the bar is low; the description adds concrete context: no API key is needed, the result matches /.well-known/agent.json, and it names the fields that are returned. It does not discuss caching, rate limits, or what happens when the hash mismatches.

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?

It is two sentences organized around a front-loaded benefit (no API key) and a call to action (validate before acting). The parenthetical field list is useful, not redundant, but the sentence is dense with jargon such as AgentContractV1 and hosted_runtime.

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?

Because an output schema exists and the annotations cover safety, the description only needs to explain purpose and workflow. It supplies both, including the cross-reference to /.well-known/agent.json. Only the relationship to verify_contract remains unclear.

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. The description does not discuss them, but the schema already states that no arguments are needed and that the owner is derived from the authenticated principal. With no parameters to explain, the default score of 4 applies.

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 gives a specific verb and resource: it fetches the hash-verifiable AgentContractV1 descriptor (version + schema_url + schema_hash) plus hosted_runtime facts. It does not name the sibling most likely to be confused with it, verify_contract; a reader must infer that this tool only reads and verifies the hash.

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?

Usage is stated clearly: fetch the contract "before acting" and validate schema_hash after fetching schema_url. It states the condition that selects this tool, but it does not name when to use verify_contract or the other siblings instead.

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