Add a figure

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

Annotations already declare this is a non-readonly, non-idempotent, non-destructive mutation. Beyond that, the description usefully discloses defaults: placement at the canvas centre when x/y are omitted, and use of the first project definition when figureTypeId is omitted.

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 short, front-loaded with the core action, and organized around placement, frame selection, and definition selection. It has minor repetition of schema-provided defaults but no wasted bulk.

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 five-parameter creation tool with no output schema and clear annotations, the description covers the important behavioral defaults. It does not explain the return value or failure cases, which would be helpful but are not essential for correct invocation.

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 is 3. The description adds meaningful defaulting semantics not present in the schema, especially for x/y placement and figureTypeId, though it mostly repeats the schema's frame and project defaults.

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 figure instance' to a keyframe using an existing figure definition. This clearly distinguishes it from sibling tools such as figure_duplicate, figure_delete, and figure_transform.

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 clearly explains the default behavior for frame and figureTypeId, giving the agent enough context to decide when to supply or omit those parameters. It does not explicitly compare against alternatives like figure_duplicate, but the usage context is clear.

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