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

Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond those annotations: no authentication prerequisite, hash-verifiability of the descriptor, and equivalence to the well-known web endpoint. These enrich the agent's understanding of provenance and trust.

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 — two sentences — and front-loads the most decision-relevant fact ('No API key needed'). The 'call this now' phrasing is mildly hyped and the emoji adds noise, but every substantive element (content, equivalence, validation purpose) earns its place.

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 full safety annotations and an output schema available, the description fully covers what an agent needs: what it returns, how to validate it, when to call it, and that no auth setup is required. There are no gaps that would cause an agent to misinvoke or misuse it.

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 0 parameters, which sets the baseline at 4. The input schema description already clarifies that the owner is derived from the authenticated principal, and the tool description adds nothing confusing about parameters. Nothing more is needed for a zero-argument 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 states a specific verb and resource: 'Fetch the hash-verifiable AgentContractV1 descriptor (version + schema_url + schema_hash) and the hosted_runtime facts.' It also disambiguates the content precisely by listing the component fields, and the equivalence to /.well-known/agent.json further pins down what this tool returns.

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 when-to-use guidance: call it to validate the platform contract before acting ('Fetch schema_url and match schema_hash to validate the platform contract before acting'). It also removes an access barrier by stating no API key is needed. No explicit alternatives or exclusions are named, but no sibling tools were provided, so the context is adequate.

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