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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=true, so the safety profile is covered structurally. The description adds genuine value beyond annotations by disclosing what the card contains (skills, endpoints, A2A versions), which is useful behavioral context about what the returned document will describe. No contradiction with 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?

A single sentence that leads with the verb 'Fetch', states the target, and appends a useful parenthetical definition of what an agent card is. Zero wasted words; every clause 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 discovery tool with comprehensive annotations and no output schema, the description fully equips an agent to call it correctly. Nothing about when, how, or what it returns is left ambiguous.

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, so there is nothing for the description to clarify. Per the rubric, a 0-parameter tool gets a baseline of 4, and the description correctly stays silent on parameters rather than inventing unnecessary detail.

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?

States a specific verb ('Fetch'), a specific resource ('Dokimo's public A2A agent card'), and explains what the card contains (skills, endpoints, supported A2A versions). The phrase 'discovery document' clearly distinguishes it from the verification-focused siblings (verify_evidence_package, recompute_merkle_root) without needing to open schemas.

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 implies this is the discovery step — you read the card to learn capabilities before verifying — but it never explicitly states when to call it versus the sibling verification tools. No exclusions or alternatives are named, so the agent must infer the usage context.

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