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

No annotations are provided, so the description carries the full burden. It discloses the mobile-number format, but omits everything else an agent would want for a side-effecting send: delivery behaviour, rate limits, cost, permissions, or reversibility. The 'sender is optional' statement also conflicts with the schema, further muddying behaviour.

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?

Purpose is front-loaded in the first clause, which is good, but the args list is crammed into the description in a raw, hard-to-parse format. No wasted sentences, but the structure is awkward rather than clean.

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 three-parameter, side-effecting send tool with no annotations and no output schema, the definition is thin. It documents parameter formats but nothing about results or operational constraints, leaving the agent under-informed about a mutation-style action.

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 0%, so the description must compensate, and it does provide meaning for all three params (sender length, body role, mobile format with example). However, it labels sender 'optional' while the schema marks it required, which misleads the agent on a key constraint.

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+resource: 'Send an SMS to a mobile number'. An agent immediately knows this is an outbound-messaging tool, distinct from the docuengine/company-lookup siblings. There are no SMS-related siblings to differentiate from, so no explicit routing is needed.

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 no when-to-use guidance, no prerequisites, and names no alternatives. It explains number formatting but not the context in which the tool should be selected over check_mobile_advanced or other mobile tools.

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