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

With no annotations provided, the description carries the full burden. It adds meaningful behavioral context: verification includes the cryptographic signature when present, and registration is self-reported and does not prove skills. However, it does not disclose behavior for missing/invalid signatures, potential failure modes, or the return format.

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 two concise sentences with no filler. The core action is front-loaded, and the trust caveat is presented as a separate, clearly worded sentence. Every element 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?

Given the low complexity (one parameter, no output schema, no nested objects), the description covers the essential purpose and an important trust limitation. It does not describe the return value or behavior for missing signatures, which would improve completeness, but the definition is still sufficiently informative for an agent to invoke it correctly.

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?

Schema description coverage is 0%, so the description must compensate. The phrase 'Fetch and verify an A2A Agent Card' clarifies that agentCardUrl is the URL of the agent card, adding meaning beyond the schema's format hint. Still, it lacks details on accepted URL schemes, error handling, or edge cases, though for a single obvious parameter this is adequate.

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 action ('fetch and verify') on a specific resource ('A2A Agent Card'), and clarifies scope by mentioning cryptographic signature verification. This effectively distinguishes it from sibling tools like get_agent, which likely only fetches agent information without verification.

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 that this tool should be used when identity verification is needed, and the caveat about self-reported registration provides some context. However, it does not explicitly mention alternatives such as get_agent or search_agents, nor does it state when not to use this tool.

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