list_categories

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

No annotations are provided, so the description should carry the behavioral burden. The tool name implies read-only (list), and the description confirms it lists categories. However, it doesn't disclose return format, pagination, or whether it returns both expense and income categories together when no type is given. The description adds some value but leaves return-behavior details unexplained despite an output schema existing.

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?

Three bullet-point-style lines, each earning its place: purpose statement, parameter clarification, and usage guidance. Front-loaded with the primary verb phrase. Zero waste.

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 1-parameter tool with an output schema present, the description covers the core purpose and parameter semantics. It's reasonably complete, though it could mention whether listing categories includes custom user-created ones versus only 'established/standard' ones—the word 'established' is ambiguous. Given the simplicity of the tool, this is adequate but not rich.

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 description adds meaning to the single 'type' parameter by specifying it filters by 'expense' or 'income', which the schema does not document (0% coverage, no enums). However, the values 'expense' and 'income' are given but no format clarification (e.g., exact string casing) is provided. With only 1 parameter, the description compensates reasonably but not fully.

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 clear verb+resource ('List established categories available for transactions') and distinguishes from sibling tools by relating to categories rather than transactions or summaries. It doesn't explicitly differentiate from add_category/update_category/delete_category, but the read-only nature and the guidance about viewing before creating provides implicit distinction.

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 tells the agent to use this tool 'to see standard existing categories before creating new ones', which is clear when-to-use guidance. It doesn't mention when NOT to use it or name specific alternatives, but the context of 'before creating new ones' ties it to the add_category sibling, providing useful contextual guidance.

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