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

The description adds meaningful behavioral context beyond the annotations: the action is irreversible, goes out under the creator's name, and must not be automated. This complements destructiveHint=true and gives the agent concrete consequences of calling the tool.

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?

Three tight sentences with no filler. The purpose is front-loaded, critical safety constraints follow immediately, and every sentence earns its place.

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 three-parameter, side-effectful tool, the description covers purpose, prerequisites, approval protocol, irreversibility, and cardinality. No output schema is present, but the description provides everything an agent needs to decide and invoke 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 67%, covering text and confirmed; the description reinforces and operationalizes those semantics by tying confirmed to explicit creator approval. It also adds a 'one channel per call' constraint that clarifies channel_url's intent, though it stops short of describing the expected URL format.

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 action ('Send a reply to a brand') and the specific resource (brand message). It also adds scoping details like 'One channel per call' that distinguish this from broader or bulk messaging tools in the sibling list.

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 gives explicit when-not-to-use guidance: never on your own initiative and never as an auto-reply. It also prescribes a precise workflow — draft, show verbatim to the creator, then call only with confirmed: true after approval — which fully directs an agent on when and how to invoke this tool.

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