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

With annotations covering readOnly and idempotent, the description adds meaningful context: results are ranked 'best first' with a match percent and trade-offs, and it never offers IFRA-prohibited materials. It does not describe pagination or result limits, but for a read-only finder this is strong.

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?

Two dense sentences with zero waste, front-loading the trigger and then the return format and mutation note. Every clause earns its place.

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?

Complete for a read-only lookup: trigger, return shape, ranking, constraint (no IFRA-prohibited), and the follow-up mutation tool are all covered. Minor gap: it doesn't say what happens if no substitutes are found, but that is a small omission.

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 both parameters are fully documented in the schema. The description does not add syntax or format details beyond saying it operates on 'one line' of a formula. Baseline 3 is appropriate when schema does the heavy lifting.

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 (find substitutes) and resource (a line's material), and clarifies that it returns single bottles and 2-3 bottle blends from the user's shelf. This differentiates it from siblings like search_materials and use_substitute.

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?

Explicitly says when to use: 'when the user lacks a material in a formula, or asks what they could use instead.' It also names the alternative tool for applying a chosen substitute ('use_substitute swaps one in'), leaving no ambiguity.

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