send_message

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

With no annotations provided, the description carries the full burden and does so well. It discloses key behavioral traits: the function returns quickly, details timing conditions (5-second threshold for immediate vs. pending results), and explains background fetching and the need to use 'get_task_result' for completion checks. It doesn't cover aspects like error handling or rate limits, but provides substantial operational context.

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 well-structured and appropriately sized, with a clear opening sentence stating the purpose, followed by bullet points for behavioral details and structured sections for Args and Returns. Every sentence adds value without redundancy, making it easy to scan and understand quickly.

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 complexity of initiating tasks with agents, no annotations, and no output schema, the description is largely complete. It covers purpose, usage, parameters, and return behavior comprehensively. However, it lacks details on error cases or authentication needs, which could be relevant for a tool interacting with external agents.

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 0%, so the description must compensate, which it does effectively. It adds meaning beyond the schema by explaining each parameter: 'agent_url' as the URL of a registered A2A agent, 'message' as the text to send, and 'session_id' as an optional identifier for conversation context. This clarifies the purpose and usage of all parameters, though it doesn't detail format constraints.

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 specific action ('sends a message to an agent') and the outcome ('returns the task status'), distinguishing it from sibling tools like 'get_task_result' or 'list_agents'. It explicitly mentions initiating a task with an agent, which clarifies the operational context beyond just sending a message.

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 provides clear context on when to use this tool: to send a message to an agent and initiate a task. It explicitly mentions using 'get_task_result' as an alternative for checking completion if a 'pending' status is returned, which helps differentiate from siblings. However, it doesn't specify when NOT to use it or compare with other tools like 'register_agent'.

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