a2a_discover

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

No annotations are provided, so the description bears full responsibility for behavioral disclosure. It mentions 'fetches the agent card and registers it,' but does not clarify side effects (e.g., state mutation), required permissions, error handling for invalid URLs, or whether duplicate registrations are handled. The description is too vague for a tool that likely modifies persistent state.

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 extremely concise: two short sentences that immediately convey the action and outcome. Every word adds value, with no redundancy or filler. It is well-structured and front-loaded for quick comprehension.

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 tool's simplicity (one parameter, no output schema), the description covers the essential purpose and basic behavior. However, it lacks details about return values, idempotency, and error scenarios. The sibling tools provide partial context, but the description could be more complete for a new user.

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 input schema has 100% description coverage for the single 'url' parameter. The description adds context (e.g., 'A2A agent' and example URL), but does not provide additional semantic value beyond the schema, such as format constraints or authentication context. A score of 3 is appropriate as the schema already documents the parameter adequately.

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 clearly states the tool's purpose: to discover an A2A agent at a URL, fetching and registering the agent card. The verb 'discover' and resource 'A2A agent' are specific, and it distinguishes from siblings like a2a_list_agents (for listing known agents) and a2a_send (for interactions).

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 implicitly suggests when to use the tool (when you have an agent URL to discover), but it does not explicitly state when not to use it or mention alternatives like a2a_list_agents for already-known agents. No usage exclusions or prerequisites are provided.

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