add_marker

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 very little: it doesn't state that this mutates project state, that it fails without an active sequence, whether a time outside sequence bounds is rejected, or what is returned. Only the 'active sequence' target is disclosed.

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?

A single front-loaded sentence with no waste, appropriately sized for a simple create operation. It is efficient but borders on under-specified rather than maximally informative.

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?

The full parameter schema compensates for the lack of parameter detail, and there is no output schema to explain. However, for a mutation tool with eight parameters and zero annotation coverage, the description leaves behavioral expectations (errors, active-sequence requirement, effect on the timeline) unaddressed.

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 all eight parameters, including the two enums and the markerType-dependent url/frameTarget fields, are documented in the schema itself. The description adds no parameter meaning beyond that, so the baseline 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 and resource ("Add a marker") plus scope ("to the active sequence"), which implicitly separates it from add_clip_marker and add_project_item_marker. It never names those siblings explicitly, so differentiation relies on the agent noticing the scope phrase.

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 scope phrase implies when this tool applies (a marker on the active sequence rather than on a clip or project item), but there is no explicit when-to-use vs. alternative guidance and no stated prerequisites such as an open project or existing active sequence.

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