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

Annotations already declare readOnlyHint=false / destructiveHint=false, and the description correctly aligns by framing this as a creation. Beyond that it adds real behavioral context: the created sequence is EMPTY, it is a prerequisite for lab_add_clip, and lab_continuity_check will 400 on an empty timeline. It omits auth/permission needs and any failure mode for a bad project_id, so it stops short of a 5.

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?

Three sentences, action front-loaded, and every sentence carries distinct weight (what it creates, the empty-state prerequisite, the downstream 400 and return value). No filler or restatement of the name.

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?

There is no output schema, so the description appropriately closes the loop by stating it returns the sequence record including its id. Combined with the empty-state and ordering warnings, an agent has everything needed to call it and use the result 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% and the schema already documents both parameters, including the 'Main Sequence' default for title and the project_id source. The description adds no format or constraint detail for either parameter, so the schema baseline of 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 (Create) and resource (sequence / Stage 9 timeline) with explicit scope ('inside a project'). The parenthetical naming of the timeline concept and the 'START HERE' framing let an agent distinguish it from lab_get_sequence, lab_list_sequences, and lab_add_clip without opening any 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-use ('START HERE to turn generated shots into something the continuity pass can read') and a concrete ordering constraint ('add shots with lab_add_clip before anything else works'). It also names the downstream sibling (lab_continuity_check) and the failure condition (400 on an empty timeline), so alternatives and prerequisites are unambiguous.

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