item_add_marker

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only states the action without explaining side effects such as whether adding a marker overwrites an existing one, whether markers are appended, or any permissions required. For a mutation tool, this is a significant 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?

The description is a single declarative sentence that front-loads the action and target, with no filler or redundant information. Every word earns its place.

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?

Given the low complexity of a marker-add operation, the presence of an output schema, and 100% parameter schema coverage, the description plus schema is largely complete. The only notable gap is the lack of explicit usage distinction among sibling marker tools, which is already accounted for in the usage guidelines dimension.

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 baseline applies. The description adds the contextual 'frame offset' for frame_id, but all other parameters are already fully documented in the schema. The description does not need to elaborate further, so a score of 3 is appropriate.

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 and resource ('Add a marker to a timeline item') and explicitly includes the frame offset. It clearly distinguishes this tool from siblings like clip_add_marker and timeline_add_marker by specifying the target as a timeline item.

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?

The description clearly identifies the target resource ('timeline item') but does not explicitly state when to use this tool over alternatives like clip_add_marker or timeline_add_marker. No exclusions or alternative tool names are mentioned, leaving usage context implied rather than explicit.

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