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

Annotations (readOnlyHint=true, openWorldHint=false) already signal no side effects, and the description adds genuine behavioral context beyond them: nothing is sent until the human taps send, the agent must show the message first, and it must never send on the human's behalf without go-ahead. That human-in-the-loop contract is not derivable from the 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?

Three sentences, each earning its place: the what/return, the safety contract, and the routing rule. The resource and destination are front-loaded before the constraints.

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?

No output schema exists, yet the description still explains the return value (message plus sms: link), covers the two required params implicitly through the message content, and specifies agent behavior. Nothing an agent needs to call and use this tool correctly is missing.

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 100% for all three parameters (name, company, message), so the schema already documents each field including the maxLength on message. The description adds no parameter-level syntax or format detail beyond what the schema provides, making 3 the appropriate baseline.

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 action (prepare a text message to the agency), names the target number, and explains the return (the message plus an sms: link prefilled in the messaging app). It explicitly distinguishes itself from the sibling create_booking_link, so an agent can route correctly without opening either schema.

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?

Names the alternative (create_booking_link) and the condition that selects it (scheduled call), then states the positive case for this tool (a quick question or asking for a call back). Both when-to-use and when-to-use-something-else are explicit.

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