List every category

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

Annotations already communicate read-only, idempotent, open-world, and non-destructive behavior. The description adds useful context beyond that: categories have numeric ids, names and ids are both accepted elsewhere, and the naming is not Apple's genre list. This adds meaningful semantic context for an agent deciding whether to consume the result before category-based calls.

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 tight sentences, both purposeful. The first states exactly what is returned; the second explains when and why to call it. No filler or restatement of the title beyond what is useful.

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 no-parameter, no-output-schema enumeration tool, the description is complete: it tells the agent what the result contains (every category and its numeric id) and why the call is worthwhile. The lack of an output schema is mitigated because the first sentence effectively describes the return shape. Nothing essential is missing.

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 takes zero parameters, and the schema is empty, so the description cannot add parameter-level meaning. Per the baseline for a 0-parameter tool, a 4 is appropriate because there is nothing missing that the description needs to explain.

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: listing every category Podcast Index uses, with its numeric id. It also distinguishes itself from the sibling list/search tools by clarifying it is the universal category enumeration, and even differentiates its names from Apple's genre list. This leaves no ambiguity about what the tool returns.

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 when to call this tool: once before filtering anything by category, because several other tools accept either the name or id and the names differ from Apple's genres. This is direct, actionable routing guidance with a clear rationale, even though there is no sibling category-specific alternative to exclude.

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