Codex Explain Code

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

No annotations are present, so the description carries the full burden of behavioral disclosure. It does not state whether the tool is read-only, whether it can make changes, how it interacts with the working directory, or what kind of output to expect. For a Codex-powered tool, this is a notable 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 concise, with the core purpose front-loaded and supporting use cases in a second sentence. There is no redundant or filler content, though it is not maximally information-dense.

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?

The description is adequate for a read-oriented explanation tool: it states purpose and typical use cases, while the schema covers parameter meaning and defaults. However, with no annotations and no output schema, the agent is left to infer return behavior and safety characteristics, and the sibling tools are not differentiated.

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 80%, so most parameters are already documented in the schema. The description itself adds no parameter-level detail and does not clarify the undocumented workingDirectory parameter, but it does not need to repeat what the schema already provides. Baseline 3 is appropriate.

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 action ('deeply explain') and the resource ('code, logic, or architecture'), making the tool's purpose immediately understandable. It does not explicitly contrast it with siblings like codex_review_code, but the wording implies explanation rather than review, critique, or implementation.

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 concrete use cases: 'understanding unfamiliar code, onboarding, or documenting complex systems.' This gives the agent clear context for when to select this tool, though it does not explicitly say when not to use it or name alternative tools.

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