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

With no annotations, the description carries the behavioral burden and does so well: it discloses the cost model ('Free, with a daily limit'), the state dependency (unmade draft from draw_presenter), the identity-preservation guarantee, and that the result is shown. It omits what happens to the original image or error behavior when the draft is already made.

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?

Four short sentences, each load-bearing: purpose, scope, output, cost/limits, and precondition. Front-loaded with the action, no filler or restated title.

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?

No output schema and no annotations, so the description must stand alone, and it covers purpose, output ('shows the new picture'), cost, limits, and state constraints. Missing only edge-case behavior such as failures or what happens to the prior image.

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 coverage is 100% so the baseline is 3, but the description goes beyond the schema by enumerating the changeable dimensions (background, outfit, hair, glasses, expression) and reinforcing the 'one thing only' constraint. That extra framing meaningfully guides how to fill the single 'change' parameter.

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 ('Change one thing about the presenter picture just drawn') and immediately scopes it ('keeping the same person'). It is clearly distinguishable from draw_presenter, make_presenter, and check_presenter because it operates on an existing draft rather than creating or inspecting one.

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?

Gives an explicit precondition: 'Only works on an unmade draft from draw_presenter,' which routes the agent to the right sibling when no draft exists. It does not spell out the negative case (e.g. what to call when the draft is already made) beyond the constraint, so it stops short of full when/when-not coverage.

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