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

The description adds significant behavioral context beyond annotations: 'uses Mailrith's durable scheduled-send path,' 'Effect: external-email,' 'Retry after reading the current resource state,' and required permissions. It also clarifies the non-immediate delivery behavior, which is crucial for an agent choosing between this and broadcasts_send.

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 description is three sentences, front-loaded with the primary purpose, and includes only essential details (durable path, effects, retry, permissions, API reference). Every sentence earns its place without redundancy.

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 the tool's moderate complexity, the description fully covers purpose, behavior, side effects, permissions, and retry guidance. With an output schema present, there is no need to describe return values. The description is complete for an agent to select and invoke this 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?

Schema description coverage is 100% for both parameters and the nested scheduled_at field. The description adds no parameter-specific semantics beyond what the schema already provides, so the baseline score of 3 is appropriate.

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 tool's function: 'Schedules a draft for future delivery, or changes the delivery time of an existing scheduled Broadcast.' This specific verb+resource distinguishes it from siblings like broadcasts_send (immediate) and broadcasts_unschedule (cancels).

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 provides clear context by noting 'does not start delivery immediately' and 'Retry after reading the current resource state,' which implies when to use it for scheduled delivery versus immediate send. However, it does not explicitly name alternative tools or state exclusions, so a 4 rather than a 5.

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