send_codex_agent_input

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

No annotations are provided, so the description carries the full burden. It only states the action but does not disclose whether the call blocks, returns immediately, or what happens if the agent is not found. The timeout parameter hints at waiting behavior but is never explained in the description.

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 sentence that front-loads the action and resource with no filler words. It is optimally concise for a tool meant to continue an existing 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?

The tool has 3 parameters and an output schema, but the description is minimal. It lacks details on timeout semantics, error behavior, or how it relates to sibling tools like session_continue. For a simple tool, it is marginally adequate but leaves gaps around behavior and edge cases.

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?

The description indirectly adds meaning to 'agent_id' (existing agent) and 'message' (new instruction), but it does not explicitly describe any parameters. With 0% schema coverage, the 'timeout' parameter is entirely absent from the description, so it only partially compensates for the schema's silence.

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 the specific verb 'continue' and resource 'existing background Codex agent', clearly distinguishing it from siblings like spawn_codex_agent (create) and wait_codex_agent (wait). It is unambiguous about the tool's function.

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 'existing background Codex agent' implies it is for already-spawned background agents, differentiating it from spawn_codex_agent. However, it does not explicitly mention alternatives or when-not-to-use conditions, so some guidance is left implicit.

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