Ask the principal to approve an action

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

Annotations declare this is a mutation (readOnlyHint=false, destructiveHint=false), and the description adds genuinely new behavioral facts: the principal's decision happens in their own terminal, the caller must not act before approval, and approval is scoped to a single attempt unless extended. It does not say what a decline does or what is returned, but the one-attempt scoping is information the annotations cannot convey.

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?

Three short sentences, zero filler, and the trigger condition is front-loaded before the constraint and the post-condition. Every clause carries actionable information.

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 6-parameter mutation tool with no output schema, the description covers the trigger, the gating rule, and the approval scope, which is enough to call it correctly. It leaves the decline path and the shape of the recorded request unstated, minor gaps given the sibling status tool covers outcomes.

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 67%, so most parameters carry their own documentation (action example 'repo.push', details, summary, sources, request_id). The description adds almost nothing parameter-level beyond reiterating that the action/work must be approved. Baseline 3 is appropriate.

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 states a specific verb and resource: it records one approval request that the principal approves or declines in their own terminal. It also implicitly separates itself from sibling twin_authorise (which decides 'ask') and twin_approval_status (which reports the outcome), so an agent can place it in the workflow without guessing.

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?

It gives an explicit trigger condition — 'Call when twin_authorise says ask and the work needs that action' — and names the follow-up gate ('Do not act until twin_approval_status says approved'). This is a precise when-to-use rule with the surrounding siblings named, rather than inferred usage.

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