marker_add

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

With no annotations, the description carries the burden. It clarifies that 'frame is an offset from the timeline start, not a timecode' and lists valid colours. However, it omits details on side effects, required timeline state, or whether markers can overlap, so transparency is partial.

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 extremely concise: two sentences, with the purpose in the first sentence and specific details in the second. Every word adds value, with no redundancy or filler.

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 simple 'add marker' operation, the description covers core semantics (frame offset, colours) but leaves gaps: no mention of required timeline existence, outcome if marker already exists, or return value. Given 6 parameters and no output schema, more detail would improve completeness.

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%, but the description adds meaning for 'frame' (offset vs timecode) and 'color' (enum of colours). Other parameters (name, note, duration, custom_data) receive no additional explanation beyond defaults, so the description only partially compensates for the missing schema documentation.

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 clearly states 'Add a marker to the current timeline', using a specific verb and resource, and distinguishes from related tools like markers_get, marker_delete, and clip_marker_add.

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?

No guidance is provided on when to use this tool versus alternatives (e.g., clip_marker_add). It does not mention any prerequisites or context where this tool is appropriate, leaving the agent with no decision support.

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