run_scheduled_messages

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

Annotations only declare readOnly=false, idempotent=false, destructive=false, openWorld=true. The description adds substantial context beyond that: due messages are sent late rather than dropped, each job is delivered once, failed jobs are not retried, it is safe to call when nothing is due, and the exact return shape. It is consistent with idempotentHint=false.

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?

Front-loads the core action in the first sentence, then layers delivery semantics, safety, return shape, and sibling routing. Every sentence carries distinct information; the dense return-value sentence is justified because there is no output schema.

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?

With zero parameters and no output schema, the description fully compensates by documenting retry behavior, the sent/failed status values, the returned fields, and safe no-op behavior. Nothing an agent needs to call it correctly is missing.

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 tool takes no parameters, and the description confirms 'No parameters,' so there is nothing to disambiguate. Per the rubric, zero params yields a baseline of 4.

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 ('send every scheduled message whose send_at time has passed and is still pending') and explicitly contrasts with the sibling tools schedule_message and list_scheduled_messages. An agent can distinguish this from the other scheduled-message tools without opening 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 explicit when-to-invoke guidance ('call this ... after their time'), names the cron alternative, states the prerequisite condition (send_at passed and pending), and routes to schedule_message / list_scheduled_messages for the other lifecycle stages. Exclusions are covered via the 'still pending' condition.

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