get_image_metadata

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

With no annotations supplied, the description carries the full burden and does well: it discloses that no bitmap data is exported, that the result is a dictionary, and that an exception is raised if no images are open — an error condition an agent must anticipate. It does not explicitly confirm the operation is non-mutating, which is the main residual gap.

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?

Front-loaded with the core statement and the performance distinction, then a scannable bullet list of returned fields. The trailing 'Returns:' block partially restates the bullets ('comprehensive image metadata'), which is mild redundancy but also the only return documentation since no output schema exists.

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 parameterless read tool with no output schema, the description supplies the field inventory, the error case, and the cost comparison — enough to call it correctly. What is missing is a statement of state effect (read-only vs. any side effects), which matters since no annotations declare it.

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 (empty schema, 100% coverage by definition), so there is nothing for the description to disambiguate. Baseline 4 applies; no misleading parameter language is present.

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 ('Get metadata about the current open image in GIMP') and immediately scopes it ('without the bitmap data'), which distinguishes it from the sibling get_image_bitmap. An agent can tell the two apart without opening either schema.

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?

Explicitly routes the agent away from the heavier alternative: 'much faster than get_image_bitmap() since it doesn't export the actual image data' and 'Perfect for when you only need to know image properties for decision making.' Clear selection context, though it never states when this tool is the wrong choice (e.g., when pixel data is actually needed).

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