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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile needs no repetition. The description repeats the 2-to-4 bound that the schema's minItems/maxItems already enforce, and adds 'side by side on the same criteria' without explaining what happens on invalid slugs or partial matches.

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 front-loaded sentence with no filler. The phrase 'from FridgeBase's comparison (slugs)' is slightly awkward packed mid-sentence, but nothing is wasted.

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 two-parameter read-only tool with no output schema, the description covers the core action but leaves the comparison result shape ('same criteria' is undefined) and slug sourcing unclear. Adequate but with noticeable gaps an agent would hit on first use.

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 50%: market is fully documented in-schema, while slugs has only min/max item constraints. The parenthetical '(slugs)' signals that slugs are FridgeBase comparison identifiers, which adds a little meaning beyond the bare array type, but the description does not clarify slug format or where to obtain them.

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?

Names a specific verb and resource ('Compare ... fridges') plus a scope (2 to 4, side by side on the same criteria) that distinguishes it from the sibling retrieval tools like get_model and search_models. It stops short of naming those siblings explicitly, so the differentiation is implied rather than spelled out.

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 2-to-4 cardinality hints at when the tool applies, but there is no explicit guidance on when to prefer this over calling get_model repeatedly, or what to do for a single model or more than four. Usage is implied rather than stated.

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