Follow up with Codex

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

Annotations only declare readOnlyHint=false and openWorldHint=true; the description adds material behavior beyond that: the thread inherits its original working directory and sandbox mode, follow-ups are serialized per thread with a timeout-then-fail model, and it enumerates the response envelope. This is substantive context the annotations cannot convey.

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?

Three tight sentences, each earning its place: purpose first, then the thread_id sourcing rule, then inheritance/concurrency/return-shape facts. No filler or restatement of the tool name.

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?

There is no output schema, so the description compensates by naming the return fields (thread_id, answer, duration_sec, warnings[], activity?, answer_file?, error?) and covers prerequisites, sandbox inheritance, and failure modes. Nothing an agent needs to invoke this correctly is missing.

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 fast/model/effort/prompt/thread_id/timeout_sec are already documented in the schema. The description reinforces thread_id provenance ('never guess one') and connects timeout_sec to the concurrency wait, which is helpful, but it does not add meaning the schema lacks. Baseline 3 applies.

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?

States a specific verb+resource (continue an existing Codex thread by thread_id) and gives concrete example uses (re-check fixes, ask why something was flagged). It distinguishes itself from the sibling codex_ask by explicitly requiring the thread_id that codex_ask produced, so an agent can route between the two without opening schemas.

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?

Explicit usage condition (continue an existing thread) plus a hard prerequisite: 'Always use the thread_id from your own earlier codex_ask; never guess one.' It also states the concurrency rule (only one follow-up per thread, concurrent calls wait then fail with 'thread busy'), which is exactly the kind of when-it-won't-work guidance an agent needs.

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