list_categories

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

No annotations are provided, so the description carries the full burden. It discloses that only custom categories (not built-in ones) are returned and that IDs and names are included, which is useful. However, it omits whether this is a read-only operation, any pagination behavior, or permission requirements.

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 sentences with zero padding; the distinction from built-in categories is front-loaded, followed by return-value clarification and downstream use. Every sentence 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?

For a zero-param list tool with no output schema, the description covers what the tool returns (IDs and names) and how they are used. The absence of pagination and auth information is a minor gap but not critical for a simple enumeration tool.

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?

There are zero parameters, so per rubric the baseline is 4. The description also provides no misleading parameter info, keeping it at the baseline.

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?

States a specific verb ('Retrieve') and resource ('all available custom expense categories') with scope ('for the organization'). Explicitly distinguishes from built-in mercuryCategory classifications, making it clearly separate from the list_transactions family.

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?

Explains the downstream use case by noting the returned IDs can filter transactions via the categoryId parameter. This gives clear context for why to call it, but does not name exclusion conditions or a strict 'when not to use' alternative.

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