send_message

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

Without annotations, the description carries the burden of behavioral disclosure. It reveals it is a mutation (sends a message), requires app review, and has a time window constraint. However, it does not disclose error behavior, rate limits, or success confirmation.

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 highly concise with two sentences and one line, front-loading the core purpose. Every sentence adds value without redundancy, making it efficient for an AI 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 description covers key contextual aspects (what the tool does, prerequisites, limitation), but omits parameter details for text and account, and does not mention return values despite an output schema existing (though not shown). The complexity of the tool warrants more complete guidance.

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 explain all parameters. It only explains recipient_id (as IGSID) and fails to describe text and account parameters. This leaves two of three parameters undocumented, insufficient for effective tool invocation.

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 'Send a DM', which is a specific verb-resource pair. Among sibling tools, only this one sends direct messages, ensuring no confusion with reply_to_comment or other communication tools.

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 important prerequisites (Meta App Review, 24-hour window) and a key limitation (paid message tag not handled). However, it does not explicitly mention when to use this tool over alternatives or provide guidance on handling paid messages.

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