download_image

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

The description fully discloses key behaviors: streaming with a 20MB cap, content-type guard, SHA-256 hashing, and a host blocklist. Since no annotations are provided, this information is critical for safe and correct usage.

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?

Three concise sentences with no redundancy. The first sentence states the purpose, the second lists technical details, and the third adds a restriction. Information is front-loaded and every sentence adds value.

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 covers the tool's purpose, key behaviors, and return value (cached file path). It is mostly complete for a download tool, but lacks details on optional parameters and how they affect behavior.

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 description mentions a '20MB hard cap' which correlates to the maxBytes parameter but does not explain it or the cacheDir parameter. With 0% schema description coverage, the tool relies heavily on the description to clarify semantics, missing the opportunity to describe optional parameters.

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 uses a specific verb 'Download' and resource 'image URL', clearly stating the action and result (cached file path). It distinguishes itself from sibling tools like 'search_images' or 'fetch_with_license' by emphasizing local disk caching and typical usage from search results.

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 mentions 'typically from a prior search_images result', providing a clear context for when to use this tool. However, it does not explicitly state when not to use it or mention alternative tools for different scenarios.

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