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

Annotations already declare it as a non-read-only, idempotent, non-destructive write, so the safety bar is covered. The description adds real value beyond that: recipients are notified by push, the reel becomes the reference video, and the create-vs-attach branching is spelled out.

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?

A single dense paragraph with the purpose front-loaded, followed by the assignment/post branching and recipient notes. Every sentence carries information; it is slightly long but not padded.

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 an 11-parameter mutation tool with no output schema, it covers what happens, the two entry paths, defaults behavior, and recipient notification. The only minor gap is not describing the return value (e.g. the created assignment id), though with no output schema that is a small omission.

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 parameter-level docs are already strong (baseline 3). The description adds the mutually exclusive semantics of assignment_id vs post_id and clarifies the recipient roles (poster usually, editor/clipper/creators optional), which the schema does not state as a whole.

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+resource ('assign a finished edit so it gets posted') and explains the mechanism (reel linked as the assignment's reference video) with a concrete analogy. It distinguishes itself from siblings like create_assignment and create_basic_edit by anchoring on the already-finished asset returned by create_basic_edit.

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?

Explicitly tells the agent to pass either assignment_id (attach to existing) or post_id (create the assignment), including that post_id is ignored when assignment_id is set. It does not, however, position this tool against sibling create_assignment/update_assignment, so the external routing is left to inference.

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