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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false, so the safety profile is covered. The description adds useful behavioral context beyond annotations by specifying the database scale, the return content (cross-database names, structural properties, drug development phase, ATC codes), and the breadth of integrated sources.

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 front-loaded with the core purpose, then query syntax, then expected results, and is reasonably well organized. It is somewhat long and duplicates query examples already present in the schema, but the examples are relevant and the density of useful information justifies the length.

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?

Given the strong read-only/idempotent annotations, complete schema descriptions for all four parameters, and an existing output schema, the description is contextually complete. It covers the search capability, query flexibility, and result composition without requiring an agent to infer missing details.

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 100%, and every parameter already has detailed descriptions with examples, constraints, and defaults. The description repeats the q-parameter query syntax but adds little new parameter-specific meaning beyond the schema, so the baseline 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 states a specific verb and resource: 'Search the MyChem.info database of 197M+ annotated chemical compounds.' It clearly distinguishes this from the sibling tools by describing it as a flexible search over chemicals rather than annotation, batch querying, or metadata access.

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 gives clear usage context by enumerating supported query types: common name, IUPAC name, InChIKey, molecular formula, ChEMBL ID, PubChem CID, DrugBank ID, and field-scoped queries. It does not explicitly compare against siblings or state when not to use this tool, so it stops short of a 5.

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