Follow up on a Codex job

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

With no annotations provided, the description carries the full burden. It discloses key behavioral traits: it returns a new jobId, advises to keep working while it runs (avoid re-checking), and states that it reuses the original working directory and sandbox. It also notes that Codex retains context from the original job. The description does not explicitly state if the operation is destructive or safe, but the nature of sending a follow-up implies a non-destructive mutation.

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 four sentences. It is front-loaded with the core purpose, then adds critical details (retains context, return value, reuse of directory). Every sentence adds value without redundancy or fluff.

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 has 4 parameters and no output schema, the description adequately explains the tool's behavior and return value (new jobId). It covers the key use case and workflow. Minor omissions like error handling are forgivable, as this is a follow-up tool that builds on existing jobs.

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 100%, so baseline is 3. The description adds valuable context beyond the schema: for 'reasoningEffort', it provides strategic guidance on when to raise or lower the effort; for 'jobId', it clarifies that it can be a previous codex_reply job. The general explanation of the tool enriches understanding of parameter purpose.

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 verb 'Send a follow-up' and the resource 'finished job's Codex thread'. It provides concrete examples of usage ('corrections, review comments, 'you missed X', 'now do Y as well') and distinguishes itself from the sibling tool 'codex_start' by emphasizing the benefit of retaining context. The purpose is specific and unambiguous.

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 states that this tool is 'far better than starting a fresh job that would begin cold', giving a clear when-to-use recommendation. It implies when not to use (when a fresh start is needed) and contrasts with 'codex_start'. However, it does not mention other sibling tools like 'codex_execute_plan' or 'codex_result', but the primary alternative is covered.

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