gemini_spawn_agent

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

Adds real context beyond the annotations: fixed command grants carry local user privileges, native_tools requires write=true and is not an OS sandbox, native effects are untracked, and the final report must be independently verified. That is exactly the kind of risk disclosure a destructive, open-world tool needs. Not a 5 only because the durability/communication lifecycle (wait, interrupt, status) is left to siblings.

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?

Dense and front-loaded: identity/return value first, then idempotency, then the permission caveats. Nearly every sentence earns its place; the 'like Codex spawn_agent' comparison is the only filler.

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, and the description does return the durable id, which is the key output. But for a tool with deeply nested permission objects (browser command_id, checks, assertions, commands array) and a destructive hint, the description does not tell the agent what the permission sub-objects do or what happens on failure. The phantom 'capabilities' parameter further weakens completeness.

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 clarifies task_name, message, workspace, idempotency_key, permissions.native_tools and the write prerequisite, which is useful. But it references a 'capabilities' parameter that does not exist in the schema, and leaves kind enum values, max_turns, permissions.commands and the whole permissions.browser checks structure unexplained.

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 and resource ('Spawn a Gemini subagent') and adds the durable return id, which makes the effect concrete. The 'like Codex spawn_agent' analogy and the unqualified 'capabilities' term slightly muddy an otherwise clear statement, and it never names the sibling it contrasts with (gemini_send_message / gemini_followup_task).

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?

Gives conditional usage advice for idempotency_key ('supply a stable idempotency_key to safely resubmit after an uncertain disconnect') and states the default kind. However, it never says when to spawn a new agent versus messaging or following up on an existing one, so the routing decision against siblings is left implicit.

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