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

Annotations only provide destructiveHint=true, which the description corroborates and enriches: it discloses that the operation mutates Text-Em-All data, sends real messages, and consumes account credits, plus the HTTP endpoint and what is returned. The credit-spend side effect is critical information that no structured field conveys.

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 mutation/credit warning is correctly front-loaded before any parameter detail, and every sentence carries information. It is dense and packed into a single paragraph with a long broadcastType sentence, but there is no filler to remove.

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 7-parameter, nested-object mutation with no output schema, the description covers the side effects, the API target, the two broadcast modes, contact shape, the fields passthrough, and the return value. An agent has everything needed to call 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%, so the baseline is 3, but the description adds cross-field meaning: broadcastType='SMS' pairs with textMessage, 'Announcement' pairs with voiceText or fields.Audio, and it explains that extra PascalCase fields merge OVER the typed fields. This dependency guidance goes beyond the per-parameter schema text.

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 ('creates + sends a broadcast to the given contacts') and even names the underlying API route (POST /v1/broadcasts). The 'creates + sends' phrasing clearly separates it from siblings like create_draft_broadcast and send_text_message without the agent needing to open a 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?

Gives strong operational context: it warns that the call mutates data and spends account credits, and explains the SMS vs Announcement branch and how to supply content for each. However, it never explicitly names an alternative or a when-not-to-use condition (e.g., use create_draft_broadcast to stage without sending), so routing guidance is implied rather than explicit.

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