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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the core behavior of resolving an identifier to an evaluated substance)Skip but does not describe return format or failure behavior. This is acceptable given the annotations, but the description itself contributes only modest behavioral context beyond them.

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 focused sentences. The first states the function; the second adds context and the key alternative. There is no repetition of schema information and no filler.

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 simple single-parameter lookup with rich annotations, the description is nearly complete: it specifies input type and what the result is (an evaluated substance). It does not describe the return structure or error behavior, but given the simplicity and the absence of an output schema, this is a minor gap.

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 the input schema already documents the single 'number' parameter. The description adds useful semantic value by excluding INS/E-numbers and pointing to jecfa_search for those, which clarifies exactly what kind of numbers are valid and which are not.

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 uses a clear verb-resource pair: 'Resolve a FEMA number or a JECFA substance number to its evaluated substance.' It also distinguishes itself from jecfa_search by explicitly excluding INS/E-numbers, so an agent can tell which tool handles which identifier type.

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 explicit routing guidance: 'For INS/E-numbers use jecfa_search instead.' It also provides context about where these identifiers appear ('flavouring literature and JECFA meeting reports'), helping an agent decide when this lookup is appropriate.

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