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

With no annotations provided, the description carries the full behavioral burden. It discloses the long-lived child process, new-thread behavior, and the profile/compact-prompt differences. However, it does not mention side effects, permissions, return format, or timeout implications beyond what schema implies. This is moderate transparency but incomplete for a tool with zero annotation coverage.

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 two sentences with no fluff. The core action is front-loaded, followed by essential caveats. It is concise and well-structured.

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 (11 parameters, nested objects, no annotations, no output schema), the description is far too sparse. It omits explanations of critical parameters like sandbox, approval-policy, and model, and does not describe the return value or error behavior. The description covers only a fraction of what an agent needs to call it correctly.

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 0%, so the description must compensate. It only clarifies that 'profile' is not supported and 'compact-prompt' is folded into developer-instructions, which addresses two of 11 parameters. It leaves cwd, model, config, sandbox, approval-policy, timeout-seconds, base-instructions, and developer-instructions unexplained. This is insufficient for an agent to use the tool effectively.

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 a specific action: 'Runs a prompt against Codex' and adds implementation detail (long-lived child, new thread). It also contextualizes its lineage by referencing the removed mcp-server tool. This is sufficiently distinct and unambiguous, even though it doesn't explicitly differentiate from the sibling codex-reply.

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 no guidance on when to use this tool versus the sibling codex-reply. It only notes differences from a removed version (profile unsupported, compact-prompt folded into developer-instructions), which is historical context, not usage selection. No alternatives or conditions are given.

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

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

With no annotations provided, the description carries the full burden of disclosing behavioral traits. It mentions the deprecated alias and timeout parameter, but does not specify side effects, error behavior when the thread does not exist, whether results are streamed or returned in full, or any authentication/permission requirements. This is a minimal disclosure for a tool that sends prompts and likely mutates session state.

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 two sentences with no redundant text. The primary purpose is stated first, followed by useful context about the tool's provenance and deprecated alias. Every phrase carries meaning, making it efficiently scannable for an agent.

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 lack of annotations, output schema, and 0% schema coverage, the description is incomplete. An agent would not know what constitutes a valid `threadId` format, how `timeout-seconds` behaves, what errors may occur, or what the response format looks like. This is a significant gap for a tool that requires a user-provided identifier and prompt.

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 coverage is 0%, so the description must add meaning to parameters. It clarifies that `conversationId` is a deprecated alias for `threadId`, which is helpful. However, it does not explain the `prompt` parameter beyond being a follow-up prompt, nor does it describe `timeout-seconds` semantics (e.g., what happens on timeout). It partially compensates for the missing schema descriptions but leaves key parameters under-explained.

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 a specific purpose: continuing an existing Codex thread with a follow-up prompt. It identifies the resource (existing thread) and distinguishes itself from the sibling `codex` tool by noting the thread is started by `codex`, making the differentiation explicit.

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 conveys when to use this tool (when continuing an existing thread, including a previous session) and implies that `codex` is for starting threads. However, it does not explicitly state 'use this instead of `codex` when a thread already exists,' but the context is strong enough. It also clarifies the deprecated `conversationId` alias, which guides parameter selection.

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