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

Annotations already mark readOnlyHint=true, and the description adds meaningful behavioral context: no account is required, only self-registered agents appear, and each row carries verification details such as grade, protocol version, and transport. This goes beyond what the annotation alone conveys, though it does not discuss pagination behavior.

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 and front-loaded with the most operationally relevant fact ('FREE, no account'). The two sentences are information-dense, though the final metaphor ('the door...') adds rhetorical color rather than strictly necessary specification.

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 read-only list tool with only three optional parameters and no output schema, the description covers the essential facts: access requirements, data source, eligibility, and returned row fields. It is slightly thin on exact output format and ordering, but the tool is simple enough that the description is largely sufficient.

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 only 33%, and the description does not explain page or limit parameters at all. The context parameter is already well documented in the schema, so the description adds nothing to parameter understanding beyond what the schema provides.

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 specifies a clear resource ('the A2A agent registry'), the population ('agents that registered THEMSELVES by serving an agent card and calling register_agent'), and the row contents. It does not explicitly name a sibling alternative, but the registry framing and self-registration mechanism differentiate it from the many other find_* tools.

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 when to use it by calling it 'the door an unattended agent can walk through unaided' and contrasting it with options that need 'a person or a voucher.' However, it stops short of naming a specific alternative tool or stating a clear when-to-use versus when-not-to-use rule.

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