list_categories

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

With no annotations provided, the description carries the full burden. It discloses the output shape ('one-line description and page count') and enumerates the category contents, which is useful behavioral context. However, it does not explicitly state that the operation is read-only or mention any potential edge cases, though 'List' clearly implies a safe read. The lack of explicit safety disclosure is a minor gap.

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 sentences, front-loaded with the main action, and every sentence adds value. It avoids fluff and efficiently covers purpose, content, and sibling differentiation.

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 tool with no parameters, no annotations, and no output schema, the description is remarkably complete. It explains what is returned, enumerates the categories, and clarifies the boundary with sibling tools. There is no ambiguity about when to invoke it.

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 input schema is empty (no parameters), so parameter semantics are trivially satisfied. The description adds no parameter details, but none are needed. Baseline for 0 params is 4, and the description does not need to compensate for any schema gaps.

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 clearly states the tool's action: 'List all rule categories in the Email Playbook with a one-line description and page count.' It also enumerates the specific categories (structure, compatibility, production, ai-generation), giving concrete scope. It distinguishes from sibling tools by directly naming list_components as handling a separate dimension.

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?

Explicit guidance is provided: 'For reusable components, use list_components instead — they live in a separate dimension and are not returned by get_playbook_rules.' This tells the agent when to use an alternative and clarifies the relationship with get_playbook_rules, which does not return categories.

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