Execute a task with Codex

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

No annotations are provided, so the description must fully disclose behavior. It mentions the returned sessionId for later feedback but does not detail potential destructive actions, authentication requirements, or the implications of the different sandbox levels. The description is partially helpful but leaves important behavioral traits unstated.

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 two sentences—first stating purpose, second listing outputs. It is front-loaded and contains no extraneous information. However, it could be slightly more structured (e.g., separating purpose and return value).

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?

Given the tool's complexity (8 parameters, 2 required) and the presence of an output schema, the description provides adequate context for primary usage. However, it does not elaborate on the meaning of optional parameters like model, reasoningEffort, or writeNotes beyond what the schema offers.

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?

All parameters have schema descriptions (100% coverage), so the description adds minimal extra meaning. It repeats some defaults but does not clarify parameter usage beyond the schema. Baseline 3 is appropriate since schema already covers the parameters.

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 starts a new Codex session to execute a plan/task in the given workspace, and lists the key return values (sessionId, agent message, file changes, commands). It is specific and distinguishes from sibling tools like codex_continue or codex_metrics.

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 explains the tool's function but does not explicitly guide when to use it vs. alternatives like codex_continue (for resuming) or codex_review. Usage context is implied by sibling names but not spelled out.

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