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

Annotations indicate no read-only, no idempotency, not destructive; description adds key behavioral details: uses an internal API (createMessage), and the idempotency_key parameter (though in schema) is described to clarify retry semantics. Does not mention rate limits or error behavior, but the description covers the mutation nature implicitly.

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 a single, information-dense sentence that front-loads the core purpose and routing rules. It wastes no words and is immediately actionable.

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?

With a comprehensive schema and a clear description, the tool is well-covered. A minor gap is lack of explicit mention of limitations (e.g., character limits) or when salesnav_send_message is preferred, but given the rich schema and annotations, this is acceptable.

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%, so parameters are well-documented. The description adds critical guidance on how to choose between recipient_linkedin_id and conversation_linkedin_id, and clarifies that in_mail_premium requires recipient id. This goes beyond the schema descriptions and is essential for correct usage.

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?

Description clearly states the verb (send), resource (LinkedIn DM), and mechanism (Voyager createMessage), distinguishing between new DMs and replies. It does not explicitly differentiate from the sibling salesnav_send_message, but the internal routing (conversation vs recipient IDs) is clear.

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 explains the two modes of usage (existing thread vs new DM) and which parameter to use for each. It does not explicitly mention when not to use this tool (e.g., for sales navigator messaging), but the context provided is sufficient for most cases.

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