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

Beyond the annotations' read-only/destructive flags, the description discloses important behavior: unaccepted fields or unrepresentable values are refused rather than silently dropped, and guesses or plausible defaults are forbidden. This gives the agent a clear model of the tool's rejection behavior, though it does not describe persistence, reversibility, or success returns.

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 with no filler. It front-loads the core purpose, then packs the key constraints—source of field names, strict acceptance policy, and the no-guessing rule—into the remaining sentences. Every sentence earns its place.

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 tool with only three required parameters and an output schema present, the description covers the essential selection and invocation knowledge: the field source, the acceptance constraints, and the expected value semantics. It does not explain return values, but that is less critical given the output schema and the small parameter surface.

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 schema already documents all three parameters. The description adds meaningful semantics by explaining where field names originate (the missing list), what value should contain ('what the person actually said,' never inferred), and reinforcing that task_id must come from move_tasks/move_plan without modification.

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 states a specific verb and resource: 'Fills in one field the signed-in person's task is waiting on.' It also clarifies that field names come from the missing list returned by move_task or move_task_draft, which distinguishes it from sibling task tools like move_task, move_task_defer, and move_task_draft.

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 gives clear context for when to use the tool: after move_task or move_task_draft returns a missing list, and only when answering one of those requested fields. It stops short of explicitly naming a sibling alternative to use instead, but the 'Only fields that task is actually asking for are accepted' restriction effectively tells the agent when not to call it.

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