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

No annotations are provided, so the description carries the full burden. It only states that the agent is opted into A2A and that ordinary communication is unaffected. It does not disclose whether the action is reversible, requires specific permissions, or has side effects beyond the opt-in. This is a minimal disclosure.

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 a single, front-loaded sentence that communicates the core purpose and a key nuance. It is efficient and free of fluff, though it omits details that would improve completeness.

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 tool that enables a feature, the description is too sparse. It does not mention prerequisites (like an existing connection), whether the toggle is reversible, or the effect of the 'enabled' parameter. With no output schema and no annotations, the description leaves significant gaps for an agent to reason about.

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 50%: 'enabled' has no description while 'connection' has a detailed one. The tool description adds no information about either parameter, so it does not compensate for the missing description of 'enabled'. The description contributes no semantic value beyond the schema.

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 ('Opt this agent into A2A') and clarifies that ordinary channel communication is unaffected, which distinguishes it from the sibling a2a_tasks and a2a_task_update tools. It is unambiguous about the tool's purpose.

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 usage (to enable A2A) and clarifies that ordinary communication is unaffected, but it does not explicitly state when to use this tool versus alternatives or mention prerequisites like needing an existing connection for private calls. The context is clear but lacks explicit exclusions or alternative routing.

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