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

readOnlyHint=true already signals a safe read operation. The description adds useful behavioral context beyond annotations: it lists returned fields, explains the date format, and discloses the stateful from="last" behavior that returns only new messages since the last call. It omits rate limits, authentication needs, and pagination response shape, but these are less critical for a read-only list tool with full schema coverage.

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 front-loaded with the core purpose, then efficiently covers returned fields, key parameter behavior, and the FireText endpoint. Every sentence earns its place and there is no filler.

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?

With no output schema, the description helpfully enumerates the returned fields, which is important for an agent to understand results. It also covers date format and the special from="last" mode. It could mention ordering or pagination response details, but for a read-only list tool with full schema parameter coverage, it is largely 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 all five parameters are already documented in the schema. The description restates the YYYY-MM-DD date format and the from="last" semantics, which the schema also covers, and does not add meaning for pp, page, or subaccount. Baseline 3 is appropriate when the schema carries parameter documentation.

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 (list) and resource (inbound SMS received on the account's FireText numbers/keywords). It distinguishes itself from sibling firetext_list_sent_messages by explicitly scoping to received/inbound messages, and it enumerates the returned fields so the agent knows what data to expect.

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 establishes clear context: use this for inbound/received SMS rather than sent or scheduled messages, which are covered by siblings. It does not explicitly name alternatives or when-not conditions, but the scope is clear enough for an agent to route correctly.

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