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

Annotations only declare destructiveHint=true; the description adds the materially important fact that delivery goes to real recipients and identifies the underlying endpoints (POST /v1/send/broadcast via /v1/campaigns/{broadcast_id}/triggers), which explains the side effect beyond the annotation. It still doesn't say whether triggering is idempotent, throttled, or how long delivery takes.

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, warning front-loaded, no filler. The endpoint reference is compact and placed after the risk statement so it never delays the critical warning.

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 mutation tool with no output schema, the definition covers risk, resource, and endpoint, which is enough to call it correctly. A brief note on what is returned (trigger id) or on asynchronous delivery would close the remaining 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%, so the schema already explains broadcast_id, recipients override, data Liquid variables, and the three ignore/duplicate flags. The description adds no parameter-level meaning beyond that, so the baseline 3 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 and resource ('Trigger an API-triggered broadcast') plus the delivery scope ('resolved recipient set'), which cleanly separates it from transactional-send siblings. It does not explicitly name the alternative tool (customerio_send_transactional_email), so the differentiation is implicit rather than stated.

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 leading '⚠️ SENDS TO REAL RECIPIENTS' gives a clear condition for caution and tells the agent this is a live-production operation, not a dry run. It stops short of naming when to prefer customerio_send_transactional_email or what prerequisites (e.g. broadcast must already exist) must hold.

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