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

Beyond the annotations (which only give readOnly=false, idempotent=true, destructive=false), the description discloses the guarded write flow, the exact error shape {error:'approval_required', approval_token, summary} returned without a token, and that dashboard guardrails still apply. This is rich behavioral context an agent needs.

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 purpose and per-lane constraints are front-loaded, and the enumeration earns its place because the cross-parameter restriction (which lanes accept auto vs auto_simple) cannot be expressed by the two independent enums. It is dense but not padded, though somewhat long as a single block.

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?

With no output schema, the description compensates by describing the approval_required response shape and the guardrail behavior, and it fully specifies per-lane mode semantics. Nothing an agent needs to invoke this three-parameter, two-required mutation 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 coverage is 67% and both enums already list values, so the lane-to-allowed-values mapping partly duplicates structured data. However, the description adds genuine meaning by explaining what approve/off/auto/auto_simple actually do and clarifying the approval_token origin, which the schema only briefly notes.

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 first sentence states a specific verb and resource with scope: 'Set what autopilot may do on its own in one lane,' and clarifies modes are per account. An agent can distinguish this from set_autopilot, set_autopilot_floor, and set_signup_approval_mode without opening any schema.

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 gives clear operational context: the guarded approval flow, how to re-call with the token, and the per-account scope. It does not explicitly route to or exclude the sibling tools (set_autopilot, set_autopilot_floor), so alternative selection is left inferred rather than stated.

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