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

Annotations provide only a title, so the description carries the burden. It indicates a read-only operation ('Read') and discloses ordering ('newest first') and scope ('both directions'). This is sufficient for a simple read tool, though it does not describe return format or side effects beyond being non-destructive.

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 a single, well-structured sentence that front-loads the primary action ('Read') and includes only relevant details. Every word earns its place, with no fluff or redundancy.

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 tool with one parameter and no output schema, the description provides sufficient context about operation and ordering. It could mention what fields are returned, but this is a minor gap given the straightforward nature of reading SMS history.

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 the single parameter 'limit', which already explains its meaning and default/max. The description adds little beyond repeating 'newest first' that is already in the schema, so a baseline score of 3 is appropriate.

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 tool reads SMS texts (sent and received) with a specific verb ('Read') and resource ('texts'). It also distinguishes itself from an inbox by explicitly noting it covers both directions, which clarifies its scope and differentiates from similar messaging tools.

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 implies when to use this tool: whenever you need the account's full message history, not just received messages. It provides context for why it differs from an inbox, but does not explicitly name alternative tools (e.g., sms_send) or state exclusions.

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