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

Annotations already declare destructiveHint=true and idempotentHint=true. The description adds useful context beyond those flags by stating that texts already sent are not undone, clarifying the blast radius of the cancellation.

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, front-loaded with the action and immediately followed by the key caveat. 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 single-parameter mutation with safety annotations and no output schema, the description covers the key behavioral detail (already-sent texts remain sent). It does not describe the response or what happens if the broadcast has already finished, but those gaps are minor.

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?

There is only one parameter, and the schema documents it at 100% coverage ('The text broadcast id'). The description adds no additional meaning about the id format or source, so this is the baseline score for a fully documented schema.

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 names a specific verb and resource ('Cancel a text broadcast') and scopes it to outgoing or scheduled broadcasts that have not finished. This lets an agent distinguish it from dialmycalls_cancel_call and dialmycalls_send_text without opening either schema.

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?

It states a clear precondition for use: the broadcast must not have finished. It does not explicitly name alternatives such as dialmycalls_cancel_call, but the call-vs-text distinction is self-evident from the tool names.

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