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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the agent knows this is a mutating but non-destructive operation. The description adds valuable behavioral context: it is async, billed per replayed record (REPLAY metric), requires VIEWER role (cannot submit), and produces a blast-radius measurement. It does not detail what the job returns or how long it takes, but the explicit 'poll with lexq_replay_status' covers the async behavior.

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 sentences with zero waste. The core action and purpose are front-loaded, and the billing, role restriction, and polling instruction are packed into the remaining sentences. Every sentence earns its place.

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 an async job submission with no output schema, the description covers the key operational facts: what it does, how it is billed, who can call it, and how to follow up. It does not mention cancellation (lexq_replay_cancel exists) or the maxRecords cap, but the schema documents maxRecords and the sibling list implies cancellation. The description is complete enough for an agent to invoke it correctly.

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 100%, so the schema already documents all four parameters. The description adds the semantic context that candidateVersionId is the version to re-evaluate against and that from/to define the date window, but it does not add meaning beyond what the schema already provides. 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 ('Submit an async job'), a specific resource ('replays a date window of past executions against a candidate version'), and a distinctive outcome ('measures the blast radius (how many decisions change)'). It clearly distinguishes this from siblings like lexq_replay_status, lexq_replay_cancel, and lexq_simulation_start by naming the async submission and the blast-radius measurement.

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 context: it is for replaying a date window against a candidate version, and it explicitly says to poll with lexq_replay_status. It also notes billing and role restrictions. It does not explicitly say when NOT to use it versus lexq_simulation_start or lexq_dry_run, but the async/billing/date-window framing provides enough context for an agent to select it.

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