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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint, covering the safety profile. The description adds no further behavioral context such as authentication needs, rate limits, or data freshness, though it does not contradict 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?

A single sentence that front-loads the verb and resource before listing sources; 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?

With a full input schema, output schema, and annotations, the description need not document parameters or return values. It covers the main source categories but omits 'bindingdb' from the source enum and offers no guidance on the query command syntax (covered by schema), so a 4.

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%, establishing a baseline of 3. The description goes beyond the schema's generic source descriptions by mapping each enum value to specific content (e.g., ChEMBL molecules and mechanisms, ZINC purchasable compounds), which helps parameter selection.

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?

It names a specific verb ('Look up') and resource ('chemical compound or drug'), and enumerates source-specific content types (ChEMBL mechanisms, PubChem properties, etc.), which clearly distinguishes it from the many lookup_* siblings in genomics and proteins.

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 the domain context (chemical compounds/drugs) but does not explicitly state when to choose this over lookup_gene, lookup_protein, or other alternatives, nor any when-not conditions. Usage is implied by the source list, so a 3.

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