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

readOnlyHint already tells the agent this is a safe read, so the description's contribution is the domain constraint about broadcasts requiring an active keyword, which is genuinely useful context. It doesn't disclose anything further about result set size or ordering beyond what the schema's pagination fields already cover.

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?

Two short sentences with no filler: the first states the operation and its output fields, the second gives the domain constraint. Front-loaded and appropriately sized for a simple list endpoint.

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 two-parameter list tool with no output schema, the description is nearly sufficient: it names the returned fields and supplies the business rule that motivates the call, while pagination is handled by the schema. Only the absence of any ordering note is a minor gap.

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% — limit and start are fully documented including ranges, defaults, and the next_start chaining hint. The description adds no parameter meaning beyond that, so the baseline 3 for a well-described schema applies.

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 ('List text-message keywords') and even names the returned fields (id, keyword, status), which unambiguously separates it from siblings like list_shortcodes or list_texts. It stops short of explicitly contrasting with those siblings, but the resource is distinct enough that an agent can select it correctly.

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 sentence 'A text broadcast must be tied to one active keyword' implies the use case (look up an active keyword before calling send_text), but it is framed as a domain fact rather than explicit when-to-use/when-not-to-use guidance. No alternative tool is named and no prerequisite workflow is spelled out.

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