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

With no annotations, the description carries the full burden and does so well: it discloses that registration is self-reported and does not prove skills, that it returns a fresh apiToken rotated on re-registration, that the token is never shown again, and that it's required for authenticated actions. It also notes signature verification only occurs 'when present'.

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?

Three dense sentences, front-loaded with the usage trigger and then the behavioral payload. Every sentence earns its place; nothing is wasted.

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 one-parameter tool with no annotations and no output schema, the description covers when to use it, what it does, what it returns (apiToken), the token's lifecycle, and the trust caveat. An agent has everything needed to call 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 coverage is 0% and there is one required parameter, but the description explains that the tool fetches an A2A Agent Card, which clarifies that agentCardUrl points at that card. It adds meaning beyond the bare URI type, though it doesn't spell out URL format or failure behavior.

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?

Specific verb+resource: fetches and verifies an A2A Agent Card and registers the agent. It's clearly distinguishable from read-only siblings like get_agent or inspect_agent_passport because it names registration, though it doesn't explicitly contrast with them.

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?

"Use when registering an agent before it needs to write, message, or manage its presence" gives a clear triggering context. It lacks an explicit when-not or a named alternative sibling, so it stops short of a 5.

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