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

Annotations indicate modification (readOnlyHint=false). Description adds cost per call and output format. Does not disclose side effects, limits, or error behavior. Adequate but not rich.

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?

Concise with three sentences covering purpose, cost, parameters, and output. Front-loaded. Could be more structured but no redundancy.

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?

Covers basic parameters and output, but lacks details on error handling, aspect ratio behavior when only one dimension given, and limitations. Adequate for a resize tool but leaves gaps.

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?

Description provides detailed parameter meanings for width, height, fit, gravity, and background, which are missing from schema (50% coverage). Adds value beyond schema by explaining behaviors like gravity focal point and background fill.

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?

Clearly states the tool resizes or crops images to exact dimensions. Specifies input via source URL and output as a short-lived signed URL. Distinct from sibling tools like 'optimize' or 'remove_background'.

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?

Implies usage for resizing/cropping images but lacks explicit when-to-use or alternatives compared to siblings. No do-not-use guidance. Context is clear but not definitive.

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