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

Although annotations already mark it read-only and open-world, the description adds meaningful behavioral detail: rate limiting to once per minute per account, a recommended five-minute polling interval, time-window semantics, and the returned reply fields. It also notes the underlying REST endpoint without contradicting the read-only annotation.

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 purpose and returned fields are front-loaded, followed by compact operational guidance. The REST endpoint detail is slightly extraneous, and the phrase 'leaves the replies available for later calls' is a bit opaque, keeping it from a 5.

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 read-only list tool with no output schema, the description supplies the return fields, time-window rules, default behavior, and polling constraints. Combined with full schema coverage and read-only annotations, an agent has enough information to invoke it 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 coverage is 100%, and all five parameters (days, limit, offset, date_start, date_end) are fully documented in the schema. The description reinforces the time-window defaults and limits but adds little beyond what the schema already provides, so the baseline 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?

States a specific verb and resource ('List SMS replies received on the account') and enumerates the returned fields (received time, Originator, Recipient, text, reference id). This clearly distinguishes it from sibling tools such as opt-out listing, contact-list retrieval, and campaign status.

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?

Provides clear operational context: time-window selection via days 1-7 or a date range up to 30 days, default days=1, and a production polling limit with a recommended interval. It does not explicitly name a sibling alternative or a when-not-to-use condition, so it falls short of a full 5.

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