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

Annotations already signal a side-effecting operation via readOnlyHint=false and destructiveHint=true, so the description does not need to restate that. It adds the E.164 requirement and lookup tip, but does not disclose other important behaviors such as costs, error conditions, or delivery confirmation. It extends the annotations only moderately.

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 two concise sentences with no filler. It front-loads the core action and gives a practical prerequisite for correct invocation.

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 simple, fully-required 3-parameter tool, the description covers the message, source number validation, and destination format. It does not describe return values or status confirmation, but no output schema is provided and the operation is otherwise straightforward enough for an agent to invoke correctly.

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%, so the schema already documents the parameters. The description reinforces the E.164 format and points to list_phone_numbers for a valid sender, but it does not add substantial meaning beyond what the schema already provides.

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 verb and resource: 'Send a text message from one of the account's RevDesk phone numbers.' This distinguishes it from siblings like place_call and list_phone_numbers, so an agent can identify it as the SMS-sending tool.

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 gives a clear prerequisite: use list_phone_numbers to find a valid 'from' number. It also positions the tool as the way to send text messages. It does not explicitly mention exclusions or contrast with voice call alternatives, so it misses the highest bar for usage guidance.

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