timeline_get_markers

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

The annotations already declare readOnlyHint=true, and the description adds valuable behavioral detail: the return format is a dict mapping frame numbers to marker info dicts with specific fields, and it explicitly handles the no-markers/no-timeline edge case by returning an empty dict. This is transparent and goes beyond the annotation.

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 concise and well-structured: a one-sentence purpose, followed by a clear return-value summary with fields and an edge-case note. Every sentence adds value, and there is no wasted text.

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, parameterless read-only tool, the description is complete. It explains what is returned, the structure of the returned markers, and the behavior in edge cases (no markers or no open timeline). The existing output schema and readOnly annotation further reduce the need for additional context.

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?

The tool takes zero parameters and the schema description coverage is 100%, so there is nothing for the description to clarify about parameter semantics. The baseline of 4 is appropriate because the description has no parameter burden.

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 'Return all markers on the current timeline,' which uses a specific verb ('return') and clearly identifies the resource (markers on the current timeline). This distinguishes it from sibling tools such as clip_get_markers and item_get_markers, which operate on different scopes.

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 states the tool reads markers from the current timeline, and it notes that an empty dict is returned if no timeline is open. It does not explicitly name alternatives like clip_get_markers or item_get_markers, but the scoping to 'current timeline' provides clear usage context.

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