marker_add

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

With no annotations, the description carries the full burden and does disclose important return behavior: both marker_index and marker_number are returned, and marker_index is the stable id for follow-up operations. It also warns that marker_number is REAPER's display id and may be reused after deletion. It stops short of describing mutation side effects, undo behavior, or error conditions.

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 definition is front-loaded with the core action and sibling preference, then gives critical return semantics, then lists argument details. Every sentence adds useful information, and there is no filler or repetition.

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, so the description appropriately explains the return values and the distinction between marker_index and marker_number. It also covers all parameters. It remains slightly incomplete on behavioral edge cases such as project state requirements or failure handling, but it is sufficient for a marker insertion 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, and it does. It documents all five parameters with added meaning beyond the schema: position is in seconds, name is a label, and color_r, color_g, color_b are each 0-255. This resolves the main ambiguities an agent would otherwise face.

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 opens with a specific verb and resource: 'Add marker.' It also distinguishes the tool from its batch sibling by saying to prefer add_markers_batch for multiple additions. An agent can immediately identify the operation and when a sibling is more appropriate.

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 names the alternative add_markers_batch and the condition for using it: multiple markers. It also explains that marker_index should be used for follow-up marker_delete, marker_edit, and markers_apply calls. However, it does not give broader when-not guidance or other exclusions.

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