Read a Codex thread

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

The readOnlyHint annotation already covers the safety profile, and the description adds useful domain-specific context by stating that it sends nothing to the thread. This meaningfully clarifies that the tool is non-participatory, not merely read-only at the data layer. It does not describe the return format, but that is a smaller gap given the annotations.

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 a single, front-loaded sentence with no filler. It immediately states the action, the target, and the key non-sending behavior.

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 simple read-only tool with two well-documented parameters and a readOnlyHint annotation, the description is largely sufficient. It is missing explicit guidance about how the returned conversation is shaped and when open_codex_thread would be a better choice, but these are minor completeness gaps.

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%, with clear descriptions for threadId and limit including default and bounds. The tool description itself adds no parameter-specific meaning beyond 'recent conversation,' which aligns with the limit parameter. Baseline of 3 is appropriate because the schema carries the parameter documentation burden.

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 uses a specific verb ('Read'), a specific resource ('recent conversation of a Codex thread'), and adds a meaningful qualifier ('without sending anything') that differentiates it from send_to_codex_thread. It does not explicitly distinguish it from open_codex_thread, so it stops short of a 5.

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 phrase 'without sending anything' implies the tool is for passive, non-mutating inspection of a thread, which gives some usage context. However, the description does not explicitly state when to use this tool versus open_codex_thread, list_codex_threads, or other siblings, nor does it name alternatives.

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