getCategories

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

With no annotations, the description carries the behavioral disclosure burden. It usefully discloses that amounts are specific to the current plan month and UTC, which is non-obvious context beyond the schema. It also implies a read-only operation via 'Returns', though it does not discuss pagination or auth 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?

Two sentences with no filler. The core behavior is front-loaded, and the timezone/month specificity is added in a second concise sentence. Every word 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?

Given the output schema exists and parameter descriptions are complete, the description covers the important behavioral nuances: grouping and month/UTC specificity. It is slightly incomplete in that it does not guide the agent toward sibling tools for single-category lookups, but that is a usage-guidance gap more than a completeness gap for invoking this 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?

Schema description coverage is 100%, so the schema fully documents both plan_id and last_knowledge_of_server. The description adds no parameter-level meaning beyond the schema, which matches the baseline of 3.

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 specific verb and resource: returns all categories, and adds the grouping dimension ('grouped by category group'), which clearly distinguishes it from getCategoryById. The scope is unambiguous and the agent can select it correctly without opening the schema.

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 implies its use case: retrieving all categories rather than a single category. However, it does not explicitly mention alternatives like getCategoryById or provide when-not-to-use guidance, so the routing is left mostly to inference.

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