compress_image

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

With no annotations provided, the description carries the full burden. It usefully discloses the auth requirement (no login), processing location (local), implementation library (sharp), and default output behavior (same directory as <name>-min.<format>). It does not explicitly mention whether the original file is preserved or whether existing output files are overwritten, but the default filename strongly implies a new file is created.

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 entire description is one compact sentence with no unnecessary words. It front-loads the core action and then packs auth, locality, and default output into a short clause. Every phrase earns its place.

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 simple image-compression tool with five fully documented parameters and no output schema, the description plus schema covers the essential invocation details: purpose, input, output location, format options, and sizing/quality controls. The lack of an explicit return-value description is a minor gap but the predictable output filename mitigates 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?

Schema coverage is 100%, so the description does not need to compensate for undocumented parameters. The schema already describes file, out, format, maxEdge, and quality. The description adds only the default output path behavior, which is useful but not a significant expansion beyond the schema.

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 ('compress'), a resource ('image'), and a concrete scope ('local, sharp, no login'), which immediately distinguishes it from the sibling tools (gen_background, remove_bg, upscale_image, remove_watermark). The default output naming convention adds further precision. An agent can confidently identify this as the local image-compression tool.

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 makes clear when to use it: for local image compression without authentication, using the sharp library. It provides context about the local/no-login nature of the operation but does not explicitly name alternatives or state when not to use it, which prevents a 5.

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