send_message

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

No annotations provided, so description covers full burden. Discloses write operation, gated execution (confirm needed), returns structured status, and counts against daily cap. No contradictions.

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?

Single sentence with clear structure: alpha note, action, two modes, gating, return type, side effect. No unnecessary words, front-loaded with key info.

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?

Covers all essential aspects of a complex tool with 4 parameters, two modes, and a gating mechanism. Missing detailed return format, but 'structured status' suffices given no output schema.

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 100%, baseline 3. Description adds value by explaining the dual-mode behavior (reply vs new thread) and the confirm gate, which goes beyond schema descriptions.

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 tool sends a message, distinguishes between replying to an existing conversation and starting a new one, and identifies key resources (thread_id, recipient_urn). It stands out from sibling tools like comment_on_post or connect_with_person by focusing on direct messaging.

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?

Explicit guidance on when to use thread_id/conversation_urn vs recipient_urn, and the requirement for confirm:true to execute. Mentions daily message cap, helping the agent understand constraints.

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