Send a message

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

With no annotations provided, the description carries full burden for behavioral disclosure. It only states the basic operation and the optional correlation_id. It fails to disclose important traits such as error handling (e.g., invalid handle), whether the message is asynchronous, authentication requirements, or any side effects. This is a significant gap for a communication tool.

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 two sentences long, with the primary action front-loaded in the first sentence and the optional feature in the second. Every word serves a purpose; there is no redundancy or unnecessary detail. It is highly efficient for an agent to parse.

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?

The tool has 3 parameters, no output schema, and no annotations. The description only covers the basic action and one optional parameter. It does not explain success/failure behavior, return values, error conditions (e.g., invalid agent handle), or timing guarantees. This leaves significant gaps for an agent to correctly interpret the tool's full behavior.

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 schema provides 100% coverage with descriptions for all three parameters. The description adds minimal extra context by explaining the correlation_id's purpose ('match a later reply'), but it doesn't enrich the 'to' or 'body' parameters beyond the schema. Given the high schema coverage, a baseline of 3 is appropriate, with only a slight increase for the added correlation_id context.

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 action ('send a message'), the target ('another agent'), and the addressing method ('by handle'). It also mentions the optional correlation_id for matching replies. This directly identifies the tool's purpose and differentiates it from siblings like 'check_messages' which is for receiving.

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: use this to send a message. However, it does not explicitly state when to use this tool versus alternatives (e.g., 'check_messages' for receiving), nor does it provide any when-not guidance or prerequisites. This leaves the agent to infer context from the tool name alone.

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