send_broadcast

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

With no annotations, the description carries full burden. It states the tool creates and immediately sends a campaign, but does not disclose potential side effects (e.g., costs, irreversibility), required permissions, rate limits, or what happens when 'scheduleAt' is used. The description is adequate but lacks depth for a high-stakes action.

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 sentences with no wasted words. The first sentence front-loads the purpose, the second provides key constraints. Perfectly sized for a tool with 13 parameters; all information is earned.

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?

Given no output schema and 13 parameters, the description covers the core action and targeting/content constraints. It lacks explanation of 'fully-qualified filter' and return value, but overall it provides sufficient context for an agent to invoke the tool 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?

The description adds value beyond the input schema by specifying mutual exclusivity constraints ('either audienceId, segmentId, topicId, or fully-qualified filter' and 'html OR templateSlug'), which are not enforced in the schema. With 69% schema coverage, the description compensates by clarifying parameter relationships.

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 explicitly states 'One-shot broadcast: create a campaign and immediately schedule it to send', clearly indicating a combined create-and-send action. It differentiates from siblings like 'create_campaign' or 'schedule_campaign' by noting it is a single-call API that mirrors Resend's broadcast API.

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 provides clear usage guidelines: 'Pass either an audienceId, segmentId, topicId, or fully-qualified filter. Provide html OR templateSlug.' This tells the agent which parameter combinations are valid. However, it does not explicitly state when not to use this tool versus alternatives like 'send_email' or 'schedule_campaign', leaving some ambiguity.

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