Codex

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It does convey that codex operates cross-Novels, that content is reusable, and that actions include storing, enumerating/reading, and deleting. However, it does not disclose side effects such as whether delete is irreversible, whether set overwrites existing entries, how capture behaves, or any permissions required. This is a meaningful gap for a tool with multiple mutating actions.

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 three sentences long, with the core purpose front-loaded, followed by a concise 'Use when' and 'Do NOT use when' with alternatives. Every sentence earns its place and there is no fluff or repetition.

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 tool with 10 parameters, 6 actions, and no output schema, the description covers the essential when/why and explicitly rules out the main alternative use case. It does not describe return formats or the precise runtime effects of individual actions like import or capture, which would be helpful given the absence of an output schema, but the input schema compensates with detailed parameter descriptions.

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 covers all 10 parameters with descriptions, so the baseline is 3. The description adds some contextual meaning by listing content types like 'voice profiles' which maps to the capture action, but it does not provide additional param-level detail beyond the schema. Since schema coverage is 100%, the description does not need to compensate, but it also doesn't enrich param understanding.

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 purpose: 'Manage the cross-Novels codex library of reusable content' and lists concrete content types (NPCs, factions, rooms, spells, adventures, voice profiles). It explicitly distinguishes itself from siblings by stating 'Do NOT use when: storing Novel-scoped content — use lore (action: set) or note (action: set).' This gives an agent a precise understanding of the tool's scope and boundaries.

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 provides explicit 'Use when' and 'Do NOT use when' conditions. It names the alternative tools (lore and note) and the specific scenario (Novel-scoped content) that should route the agent away from codex. This is the highest level of usage guidance.

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