get_icon

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

With no annotations, the description carries the full burden. It usefully discloses the return shape ('SVG source is returned as text') but says nothing about failure behavior when an icon is not found, ambiguity resolution beyond the schema's fallback note, or rate/auth limits. Partial coverage of the behavioral surface.

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 tight sentences, front-loaded with purpose, then invocation rule, then return type. No filler or repetition of the tool name.

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 4-parameter read tool with no annotations and no output schema, the description covers purpose, invocation and return type. It omits error/no-match behavior and disambiguation guidance, leaving gaps an agent might hit in practice.

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%, so the baseline is 3. The description adds genuine value by explaining the either/or resolution strategy — exact name alone, or all four identifying fields together — which is an invocation constraint not spelled out in the schema itself.

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 verb (Fetch) and resource (SVG content of an icon) with the source named (bioicons.com), which is clear and concrete. It does not, however, differentiate itself from siblings like get_icon_info or download_icon, which an agent could confuse with this one.

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 gives invocation guidance ('Provide either the exact icon name or all four identifying fields'), which helps the agent know how to supply parameters. It says nothing about when to choose this tool over get_icon_info or download_icon, so alternative selection is left to inference.

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