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

Goes well beyond the annotations: it discloses zero cost (no model call, no date, no token, no shared daily budget), the owner-only authorization requirement, and the guarantee that the persisted result is unchanged — consistent with readOnlyHint and idempotentHint. It also states the return shape, which 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?

Front-loads the most decision-relevant fact (free, no budget), then the action, then constraints, then return shape — a sensible order. It is somewhat dense and the enum re-listing partially duplicates the schema, but each clause carries information an agent needs.

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 supplies the return structure ({sliding_doors: {original, alternate}, cost}), and it covers cost, authorization, and side-effect guarantees. Nothing material for a correct invocation appears to be 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 100%, so the baseline would be 3, but the description adds real meaning to the enum values — notably that 'bolder' shifts chance swings on every number and on trust, and that 'long_game' is scored for long-term compatibility. That is interpretive detail the schema's one-line enum descriptions only partially convey; agent_id is left to the schema.

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: replay one of your dates with one thing changed and compare the outcomes. The phrase 'the real result never changes' makes clear this is a counterfactual simulation rather than the real date, which distinguishes it from siblings like go_on_date or reflect_on_date.

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 clear situational context — free, no model call, no date/token/budget consumption — which tells an agent to prefer this over a costly real playthrough when exploring hypotheticals. It also states an access precondition ('Owner only'). It stops short of naming a specific alternative sibling for the non-simulated case.

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