compress_image

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 discloses the macOS sips dependency and the iterative binary approximation algorithm for size control, which are valuable. However, it omits whether the original file is modified or a new file created, supported formats, and error behavior in case of failure.

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: two sentences covering all key aspects without fluff. It uses bullet-point-style enumeration for clarity and prioritizes the most important usage modes prominently.

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 description lacks information about the return value or output (e.g., path to compressed file), acceptable formats, and side effects. Given no output schema, the description should fill this gap to be fully complete for an agent.

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 baseline is 3. The description adds value beyond the schema by explaining the default width (800px), the target size format (e.g., '1M'), and the iterative algorithm for maxSize. This enriches parameter understanding without being redundant.

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 states it compresses local image files, names the dependency (macOS sips), and enumerates two distinct modes: width-based and target-size-based. This specificity distinguishes it from sibling tools like 'describe_image' which serves a different purpose.

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 provides guidance on when to use each mode (maxWidth vs maxSize) but does not explicitly contrast with sibling tools or state when to choose compression over other operations. The context is clear for the tool's internal options but lacks tool-selection guidance.

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