roll_clip_join_tool

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

With no annotations, the description carries the full behavioral burden and does so well: it declares the operation is undoable, atomic on failure ('nothing changes'), enforces an abutting-clips precondition, and specifies the error code returned when violated. It also clarifies that the pair keeps its length and later clips stay put, which an agent could not infer otherwise.

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-loaded with the core operation and its directionality, then the precondition and alternative. Dense but every sentence adds operational value; the parenthetical error-code and cross-references are useful rather than padding.

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?

Output schema exists so return values need no explanation, and the description covers undoability, preconditions, and failure mode for this mutation. The only gap is the undocumented project_path parameter, which slightly reduces completeness for a 4-parameter tool.

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 0%, so the description must compensate. It gives strong semantics for delta_sec (units = source seconds, sign convention, direction of movement) and implicitly defines left/right via 'left clip' and 'right clip', but project_path is never mentioned. Partial compensation, so a baseline-3 is warranted.

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?

Specific verb ('Roll') plus resource ('the join between two neighbouring clips') with the exact effect of a positive delta spelled out. It clearly distinguishes itself from related siblings such as trim_clip_edge_tool, set_clip_join_tool, and crossfade_joins_tool.

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?

States the precondition (clips must abut within join tolerance), the failure behaviour (refused with error_code roll_needs_abutting_clips), and names the explicit alternative for the non-abutting case ('Use trim_clip_edge_tool to move one edge and ripple instead'). This is textbook when/when-not/alternative guidance.

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