message_send

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

Annotations are neutral; description adds that messages are received via message_inbox, implying persistence and async delivery, which is useful context beyond annotations.

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?

Concise and well-structured: main purpose first, then usage guidance, then parameter details. No unnecessary words.

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 simple send tool, it covers parameters, usage, and async behavior. Output schema exists so return values need not be described. Could optionally mention that messages are persisted, but not necessary.

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 Args section explains each parameter (to: agent_id or 'broadcast', body: message body, subject: optional triage). The input schema has no descriptions, so the description fully covers semantics.

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 it sends a message to another agent's inbox, and distinguishes it from the sibling tool message_inbox (which retrieves messages).

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?

It provides explicit use cases (delegating, sharing, asking, notifying) and notes async nature, but does not explicitly state when not to use it.

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