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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), so the description's job is to add context. It does add one genuinely useful fact: price and ratings are not returned but live on the model's site page, plus that each market has its own catalog. It says nothing about the 50-item cap, default result count, or what happens when filters match nothing.

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 dense sentence that front-loads the action and resource, then the markets, then the inputs, then the returns. It is slightly run-on in the trailing parenthetical, but every clause carries information.

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?

With no output schema, the description usefully enumerates the returned fields and points out where price and ratings actually live. Given a 4-parameter tool with one nested object, the remaining gap is minor: no mention of pagination via limit or empty-result behavior.

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 75%, so the baseline is 3. The description reinforces that query is free-text need and filters are exact, but largely restates the schema for market ('us = Amazon.com, in English') and adds nothing on limit semantics or the shape of nested filter values.

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 gives a specific verb and resource: search FridgeBase's fridge comparison catalog, with the two supported markets named explicitly. It is clear what the tool does, though it never names a sibling (compare_models, get_model, list_filters) to sharpen the boundary, so it is one step short of a 5.

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 through 'by need (free text) and exact filters,' which suggests a query-plus-facet search versus something narrower like list_filters. There is no explicit when-to-use or when-not, and no guidance on choosing between this and compare_models or get_model for downstream lookups.

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