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 useful context about what kind of values are returned and their role in classification/filtering, but does not disclose additional behavioral details such as output structure, which is partially covered by the output schema.

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, front-loaded sentence states the purpose, enumerates the value categories, and gives usage guidance. Every clause earns its place, with no redundant wording or repetition of schema or annotation information.

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 zero-parameter, read-only reference lookup with an output schema and full annotation coverage, the description is complete. It tells the agent what the tool returns, when to call it, and how to use the results, leaving no critical 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?

The tool has zero parameters, so there is nothing for the description to explain about inputs. Per the baseline for zero-parameter tools, a score of 4 is appropriate; the description instead focuses on the meaning and use of the returned values.

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 specific verb ('look up') and names the resource ('valid accounting values'), then enumerates concrete categories: operation types, transaction statuses, cost-basis methods, and lot event kinds. This clearly distinguishes it from sibling tools like get_filter_options or list_accounting_rules.

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 explicitly states when to use the tool: 'before classifying or filtering,' and advises using the returned exact values instead of guessing. It does not mention alternative tools or when not to use it, so it falls just short of full guidance.

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