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

Beyond the annotations, it discloses that the image goes first in panel history, becomes selected and the shot thumbnail, earlier panels remain in history, and all shots/images are validated before writing. It also states no images are generated, no credits are spent, what is returned, and the 50-shot limit, giving rich behavioral context for a non-readOnly mutation.

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 dense but front-loaded: purpose and behavior appear first, followed by alternatives, input provenance, validation, cost, return shape, and limits. Every sentence adds actionable information for calling the tool correctly.

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 write tool with no output schema, the description covers what is written, what happens to existing history, validation behavior, absence of generation/credits, return values, and limits. An agent has enough information to invoke it correctly and interpret the result.

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 already 100%, and the schema documents shotId, mediaId, projectId, the one-image-per-shot constraint, and the 50-item maximum. The description mostly repeats the same ID sources and limits rather than adding substantial new parameter semantics, so the baseline 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 states a specific verb and resource: it sets stored images as shots' selected panels, like dropping an image on a Storyboard panel. It also distinguishes this from creating shots with attachments and from redraw-board workflows, so the agent can tell it apart from siblings.

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 says when to use this tool (shots that already exist), when to use alternatives instead (create_shots attachments with mode "as-is" for new shots, or board attachments for redraw behavior), and where mediaIds come from. The alternatives are named directly, leaving little inference.

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