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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, so the agent knows it's safe. The description adds context about the return fields and identifier conversion, but doesn't disclose additional behavioral traits like rate limits or authentication requirements. This is adequate given the annotations.

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 two sentences, front-loaded with the main function, and includes an additional capability (identifier conversion) without redundancy. Every word adds value.

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?

The tool has an output schema (not shown) and the description summarizes the return fields. Given the simple one-parameter tool with comprehensive annotations, the description is complete enough for an agent to understand the tool's capabilities.

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% and the parameter description includes examples (e.g., 'caffeine', '50-78-2'). The description reinforces that the tool returns SMILES, InChI, etc., and mentions identifier conversion, which adds marginal value beyond the schema. Baseline score of 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 clearly states the tool looks up a compound by name or identifier and returns chemical structure representations (SMILES, InChI, InChIKey, molecular formula, molecular weight). It also mentions conversion between chemical identifier formats, which distinguishes it from sibling tools like chemistry.pubchem.properties or chemistry.pubchem.search.

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 description indicates when to use the tool (to look up a compound by name/identifier and get structural representations). It doesn't explicitly state when not to use it or provide alternatives, but the purpose is clear and the sibling context gives implicit guidance.

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