compare_molecules

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

No annotations exist, so the description carries the full load — it discloses the algorithmic behavior (MCS computed, shared scaffold kept neutral for contrast) and that the result is a figure rather than prose, which is meaningful behavioral context. It stops short of stating failure behavior for unresolvable names or whether a file is written, which are the remaining gaps for an annotation-free tool.

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?

Front-loaded with the core definition, then usage, then exclusions, then args — a rational order with clear sectioning. The conversational-trigger paragraph is slightly padded and repeats the ibuprofen/naproxen example already used earlier, costing a point.

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 an output schema present, return values need no explanation, and the description covers scope, exclusions, and all three parameters. The only thin spot is edge-case behavior — what happens with fewer than 2 structures, more than 4, or an unresolvable name.

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 0%, so the description must compensate, and it does: structures accepts 2-4 English/IUPAC names or SMILES, labels are per-panel display names that are localizable, and title is an optional localizable heading. This adds real meaning beyond the bare schema types and closes the coverage gap.

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 and resource ('Compare 2-4 molecules side by side') and explains the mechanism (maximum common substructure with non-shared parts highlighted), which tells the agent exactly what the output depicts. It also names the siblings it is not (generate_molecule, batch_generate), so it is distinguishable without opening any schema.

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?

Gives explicit when-to-use triggers ('user wants to compare structures', 'study a drug class'), an explicit not-for clause with named alternatives for both exclusions, and even a conversational trigger word ('difference'). Nothing is left to inference.

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