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

Annotations already declare readOnly, idempotent and openWorld, so the safety profile is covered. The description adds genuinely useful behavior: the cover crop keeps the center subject, private addresses are refused, decoded size is capped at 10 MB, and output is base64 PNG.

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?

Front-loaded with the action and preset list, then constraints and return format. The eight-preset enumeration is long but each entry earns its place by giving dimensions an agent would otherwise lack; no filler sentences.

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 input forms, security limits, crop behavior, and output format; with an output schema present it need not explain return values further. Nothing an agent needs to call it correctly is missing.

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 baseline is 3, but the description goes further by spelling out the exact pixel dimensions for each enum value and reiterating the base64/URL input paths and the 10 MB cap, adding meaning beyond the schema's terse enum description.

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+resource ('Crop and resize an image') and enumerates all eight presets with exact pixel dimensions, which clearly separates it from the sibling resize_image and crop_image tools.

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?

Usage is implied by the preset list ('to an exact social media preset'), but it never states when to choose this over resize_image or crop_image, nor any prerequisites. No explicit exclusions or alternatives are offered.

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