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

Annotations already establish readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds genuinely useful disclosure beyond that: it enumerates what the comparison returns (roast, sensory scores, shared vs distinct flavors, brew methods, price delta), which matters because there is no output schema. It does not cover failure behavior for an unknown coffee id/name.

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 compact fragment, front-loaded with the operation and then the compared dimensions. Every listed item earns its place by telling the agent what the comparison surfaces; there is no filler.

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 correctly takes on the burden of describing return content, which it does well. What is missing is routing context against the sibling tools and any statement about invalid or unresolvable coffee identifiers.

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% and both required parameters are documented in the schema as 'id or name' with maxLength. The description adds nothing about how coffee_a and coffee_b are supplied or whether order matters, so the baseline 3 applies.

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 operation (side-by-side comparison) and enumerates the compared attributes: roast, body/acidity/sweetness, flavors, brew methods, price. It is clearly distinguishable from get_coffee or find_similar by scope. It stops short of naming those siblings explicitly, so it is clear but not sibling-differentiating.

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?

There is no when-to-use guidance and no mention of alternatives such as find_similar or get_coffee, which an agent could plausibly reach for instead. The two-input comparison is only inferable from the field list, so usage must be inferred rather than read.

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