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

With no annotations and no output schema, the description carries the full burden of explaining behavior. It says the tool compares pack sizes and reports a percentage, but it does not explain what happens when no cheaper pack exists, whether multiple matches are possible, or what shape the response takes.

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?

The description is short and front-loads the comparison concept, but it is grammatically incomplete and lacks a clear main verb. It is concise, though not as clearly structured as it could be.

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 simple one-parameter analytical tool, the description gives the core comparison concept. However, without an output schema it should more explicitly describe the return values and the no-match case.

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 deal parameter is already well documented with an example. The description adds useful provenance by saying the slug is returned by unit_price, but it does not add syntax or matching details beyond the schema.

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 identifies the resource and comparison: one tracked listing, the same product in a different pack size, the per-unit savings, and the percentage. It is specific enough to distinguish this from a plain unit-price lookup, though it is phrased as a fragment rather than a clear action.

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 only usage clue is that the deal slug comes from unit_price. There is no explicit statement of when to use this tool instead of unit_price or category_price, and no exclusions or prerequisites are given.

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