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

Goes beyond the annotations by disclosing that the customer sees the message immediately, that the conversation then lives in Messages, that calls require confirmation by default (toggleable), the trust requirement to confirm before reaching other people, and the Cotlet API key requirement. That is meaningful behavioral context for a mutation 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?

Heavily repetitive: 'first message' is restated three times and 'conversation moves/lives in your Messages' appears twice. The core action plus the confirmation and key notes could be stated in half the length without losing information.

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 3-param mutation tool with no output schema and annotations that already signal an external, non-destructive write, the description covers effect, auth, and confirmation behavior adequately. Only the absence of return/pagination detail keeps it from a 5.

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 the schema already documents lead_id, body, and attachment_urls. The description's note that photos/files are attached 'by URL' restates the schema rather than adding syntax or constraints, so the baseline of 3 applies.

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?

States a specific verb and resource ('Send your first message to a lead'), and the 'first message' framing distinguishes it from the ongoing-conversation siblings like thumbtack_send_message. It stops short of explicitly naming those alternatives, so the distinction must be inferred.

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 'first message' framing implies the use case (initial outreach to a lead), which is better than nothing. But it never names a sibling or states when to prefer it over thumbtack_send_message, thumbtack_reach_out_to_opportunity, or thumbtack_send_estimate, so the routing is left to inference.

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