Create Timeline Marker

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

With empty annotations, the description carries the burden and is fairly transparent: it discloses the C4D call used, that creation is one call, that markers can be named, and that the call returns marker info including an index handle. It does not detail failure conditions or permissions, but for a create operation with a stated return value this is a minor gap.

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 dense sentences front-load the core behavior, then add rationale and return-value context. No filler or repetition of schema fields.

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, but the description supplies the important return detail (marker info with an index handle for follow-up tools). Combined with 100% parameter schema coverage, an agent has enough context to call this 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%, so the schema already documents all five parameters with defaults and mutual-exclusion notes. The description adds only a light summary ('optional colour and length', 'frame (or time in seconds)') rather than new parameter meaning.

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 uses a specific verb ('Create') and resource ('named timeline marker'), and specifies frame/time positioning plus optional color and length. It distinguishes create_marker from sibling operations by noting the returned index is intended for set_marker/remove_marker.

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 explicitly says this replaces the old playhead-seeking workaround and explains why (that approach could only create unnamed markers). It also routes subsequent edits/deletes to set_marker/remove_marker via the returned index.

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