download_icon

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

With no annotations, the description carries the full burden of behavioral disclosure. It usefully discloses the quota cost (150/day on the free trial), the public-domain-only restriction on the free trial, and the optional color/size behavior. It does not describe the return representation (e.g., raw bytes vs file written via save_to_file), which is a minor gap but the disclosed constraints are meaningful.

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 short sentences with no wasted words. The core action and formats are front-loaded, and the usage boundary and quota warning are relevant additions. The phrase 'expensive *icon* call' is slightly informal but efficient.

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 when to use, quota, and licensing restrictions, which is good for a tool with no annotations and no output schema. However, it does not explain what the tool actually returns when save_to_file is omitted, nor how download success is conveyed, leaving a meaningful gap for an agent deciding how to present the result to the user.

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 schema already documents all five parameters. The description adds only that color/size are optional and that size applies to PNG, but those details are already implied by the schema. It does not introduce substantial new parameter meaning beyond the structured definitions.

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 action ('Download one icon') with explicit formats (SVG or PNG) and modifiers (color/size). The description distinguishes it from inspection workflows by clarifying it is for saving/embedding, not inspecting search results, which separates it from sibling tools like get_icon and search_icons.

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 says to use it only when the user asked to save or embed the file, and not to inspect search results. This gives a clear when/when-not boundary, but it does not name the specific sibling tool that should be used for inspection, so the guidance is strong but not maximally explicit.

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