Codex Explain Code

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It conveys the semantic intent (explain/understand/document) but doesn't disclose key behavioral traits: it doesn't state whether this is read-only, whether it modifies files, whether it has rate limits, mutates state, or sends code to an external service. It adds context about the purpose but omits operational behavior.

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, front-loaded with the core purpose, then use cases. No wasted words. A third sentence naming alternatives could have improved the differentiation but the current length is appropriate and efficient.

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 relatively simple explanation tool with a well-documented schema (80% coverage) and no output schema, the description is moderately adequate. It captures the intent and use cases. However, the absence of any behavioral/operational disclosure (read-only? external service? cost implications?) and minimal sibling differentiation leave gaps that reduce completeness, especially given the large sibling set.

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 coverage is 80%, meaning most parameters are documented in the schema itself. The description adds value beyond the schema by contextualizing the tool's overall purpose, which helps interpret 'target' and 'context' semantically. The 'depth' enum is already well-described in the schema. The description doesn't add per-parameter detail beyond schema, but with high coverage that's acceptable.

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 clear verb+resource ('Ask Codex to deeply explain code, logic, or architecture') and lists use cases. However, it doesn't explicitly distinguish from sibling tools like codex_query or codex_review_code, though the 'deeply explain' phrasing implies a pedagogical intent that differs from query or review.

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 gives useful when-to-use context ('understanding unfamiliar code, onboarding, or documenting complex systems') but doesn't explicitly contrast with alternatives like codex_review_code (review) or codex_query (search). No when-NOT-to-use guidance is provided, and with several siblings, explicit differentiation would be valuable.

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