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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so safety is covered. The description adds value beyond that: a 60-second cache window, the fact that it is a 'MAT catalog read, like the list', and that retry_key returns the same read for five minutes. It does not cover auth or error 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?

Front-loaded and dense, but the second sentence re-enumerates nearly everything the first sentence already listed ('every skill', 'capabilities', protocol version, documentation), which is genuine redundancy rather than added value. The incremental detail (icon URLs, first-seen date) is buried inside the repetition.

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?

With no output schema, the description carries the return-value burden and does describe the payload (skills, capabilities, protocol version, docs/icon URLs, registries with licenses, first-seen date). It is complete enough to call correctly, though the duplicated enumeration slightly muddies what is actually returned.

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 100%, and the schema already says chave is the 'key from a2a_agent_search' and documents retry_key's length and five-minute reuse. The description largely restates the schema's key provenance, so baseline 3 is appropriate.

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 and resource ('Read one A2A agent') and immediately names the returned fields, so it is clearly distinguishable from the sibling list tool a2a_agent_search. An agent knows this is a single-item detail read without opening any schema.

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?

'Take the key from a2a_agent_search' explicitly routes the agent to the prerequisite tool and names the source of the required parameter. There is no explicit when-not or exclusion, but the single-item vs list split with the sibling is clear.

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