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

With no annotations, the description carries the full behavioral burden. It does convey key output traits: 'direct PNG download URLs', sizes ranging 16-512px, and 'transparent background'. However, it does not mention any error behavior, rate limits, or whether an invalid id returns no URLs or fails, so it falls short of full transparency.

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?

A single sentence conveys the tool's core purpose, output type, size range, transparency trait, and input requirement without redundancy. It is front-loaded and wastes no words.

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 small, well-documented two-parameter tool with high schema coverage, the description is mostly sufficient. It omits an explicit return-shape explanation for the 'all sizes' case, but since output schema is absent and the schema already covers the optional size parameter, the description plus schema should allow an agent to invoke the tool correctly.

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 description coverage is 100%, with both 'id' and 'size' already documented in the input schema. The description adds the PNG/transparency context but does not elaborate on parameter behaviors beyond what the enum and property descriptions already provide. Baseline 3 applies.

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 a specific verb ('Get'), a specific resource ('direct PNG download URLs'), and a scope ('for an Infyicon icon id'). The explicit mention of 'PNG' naturally distinguishes it from the sibling tool get_icon_svg.

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 it obvious that the tool is for retrieving PNG download URLs and implicitly not for SVG retrieval, but it does not explicitly name alternatives or state when not to use this tool. The context is clear but lacks explicit exclusions.

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