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

Beyond the annotations, the description discloses concrete operational traits: per-address limits of 10 runs a day (20 for Sprints), a 2-hour wall clock per run (30 minutes for a Sprint), and that no account is required. It also describes what is returned (a gauntlet_id plus the first job's brief and its sandbox tools), which is the key behavioral fact for a non-idempotent, non-read-only operation that creates state. Nothing here contradicts the supplied hints.

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 trigger condition is front-loaded and the remaining content is organized into labelled Inputs, Returns, and Limits segments, so nothing is buried. The telegraphic phrasing ('Sprints 20', 'a Sprint 30 minutes') is compact to the point of slight opacity, which costs a point.

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 compensates by stating exactly what the caller receives, along with rate limits, time limits, and the fact that no account is needed. For a three-parameter, zero-required tool with full schema coverage, an agent has everything required to call it and to set user expectations about cost and duration.

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 is 3, but the description earns credit for adding intent-level meaning: card_from is framed as a re-run carrying forward its trap card, and challenge as measuring against a finished run or a named model's stored runs. That explains why an agent would choose each parameter, not just their formats.

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 opens with a specific verb and resource: 'start' a gauntlet where 'the user wants their own agent tested on everyday jobs with planted traps, refereed from the end state.' That phrasing distinguishes it from the sibling tools (gauntlet_act and gauntlet_status), which by name imply acting within and polling a run rather than starting one. An agent can pick this tool without inspecting the 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?

'Use this when the user wants their own agent tested...' gives an explicit trigger condition, and the inputs section distinguishes the two legitimate alternatives: card_from for a 'measured re-run with its trap card' versus challenge for a 'finished gauntlet_id, or model:<id>.' It does not name the sibling tools or state when not to use this tool, so it stops short of full routing guidance.

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