fill

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

No annotations are provided, so the description carries the full burden. It adds context about the return value ('Returns the updated grid so you can verify the result') and implies a mutating operation ('Flood fill'), but it does not disclose potential side effects, permission requirements, or reversibility. This is a notable gap for a mutation tool.

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 extremely concise, consisting of two short sentences that front-load the core purpose and mention the return value. Every word earns its place, with no redundant information.

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?

The tool is simple and the description covers the essential aspects: what it does (flood fill), where it operates (on a canvas), and what it returns (updated grid for verification). The detailed schema covers parameters, and the description is sufficient for an agent to correctly select and invoke the tool. It lacks only explicit usage guidance and more thorough side-effect disclosure, but these are not critical for such a straightforward operation.

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 schema has 100% coverage with descriptions for all parameters (x, y, color, canvas_id). The description does not add parameter-specific meaning beyond what the schema already provides, so it meets the baseline for high schema coverage.

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 clearly identifies the tool as a flood fill operation on a canvas ('Flood fill from a point on a canvas') and specifies the return value ('Returns the updated grid so you can verify the result'). This distinguishes it from sibling tools like pixel, line, and rect, which perform other drawing operations.

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 implies usage (use when you need to flood fill a region), but it does not explicitly state when to use this tool versus alternatives like pixel, line, or rect. No exclusion criteria or alternative tool names are mentioned.

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