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

Annotations declare readOnlyHint=false, idempotentHint=false and destructiveHint=false, covering the safety/mutation profile. The description adds useful behavior beyond that: the edit is in place, it uses the app's own amounts, and it preserves dilution/smell and merges into an existing line. It does not address reversibility or what happens to the replaced material.

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?

It is a single sentence, which is structurally economical, but it is a dense run-on laden with poetic filler ('the same smell carried through each bottle's dilution') that does not earn its place. The usage trigger is front-loaded, but the rest reads as atmosphere rather than specification.

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 3-parameter mutation tool with annotations and no output schema, the description covers the trigger and some effect semantics (in-place, merge, amounts), which is adequate. It is still vague on the precise result of the swap and on whether the prior line content is discarded.

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 all three parameters (line, formula, members) are already documented in the schema. The description only echoes 'pass its member names,' adding no syntax or format detail beyond what the schema provides; baseline 3 is appropriate.

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 does convey the operation ('replaces the line with it... pass its member names') and ties it to a specific sibling, find_substitutes. But the flowery phrasing ('the same smell carried through each bottle's dilution, merged into a line that already holds that bottle') obscures the exact effect, leaving the core purpose only half-graspable.

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?

It states a clear triggering condition: 'Use this when the user picks one of find_substitutes' suggestions,' which routes the agent from the discovery tool to this mutation tool. No when-not condition or other alternative is offered, but the context is explicit.

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