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

The description discloses that messages are 'rendered and sent' at the scheduled time, and notes that 'past times are bumped to now.' This adds important behavioral context beyond the 'destructiveHint: true' annotation, which only indicates side effects.

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 sentences long, front-loads the core purpose, and wastes no words. Every sentence adds value.

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?

The description covers the main purpose and usage but does not explain what the function returns (no output schema). It also omits details like whether scheduling can be edited or cancelled. Given the tool's simplicity, it is adequate but not complete.

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 baseline is 3. The description does not add new meaning beyond what the schema already provides for each parameter.

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 ('schedule'), resource ('SMS text message'), and key differentiator ('at a future time instead of sending immediately'). It distinguishes from the sibling tool 'send_sms' which likely sends immediately.

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 explicitly provides a use case: 'time a reminder or follow-up to the lead's timezone.' It also implies when not to use it (immediate sending) via the phrase 'instead of sending immediately.' However, it does not explicitly name alternatives like 'send_sms'.

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