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

The annotations declare idempotentHint=false, but the description asserts the opposite behavior: 'replaying it returns the existing run instead of launching twice' — i.e., repeated calls with the same arguments have no additional effect, which is exactly what idempotentHint=true means. This is a direct mismatch between the stated behavior and the structured hint. The description's other disclosures (token spend, billing, hard-ceiling rejection, staleness rejection) are valuable, but the idempotency conflict triggers the contradiction rule.

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?

Four dense sentences, front-loaded with the action and the cost warning ('SPENDS TOKENS') before prerequisites and edge cases. Every clause carries operational information; nothing is padding.

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 4-parameter launch tool with no output schema, the description covers cost, required inputs, rejection conditions, retry path, idempotency behavior, and the return value ('Returns run_id'). An agent has everything needed to call 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 quote_id, quote_hash, idempotency_key, and the max_tokens hard ceiling; the description largely restates those (stale hash, no clamping, replay protection). The only marginal addition is the 're-quote and retry' workflow for rejected quotes. Baseline 3 is appropriate when the schema carries parameter meaning.

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 ('Launch the quoted simulation') and clearly positions the tool at the end of the mcg_quote -> mcg_run workflow. An agent can distinguish it from mcg_quote, mcg_get_run, and mcg_list_runs 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?

Gives explicit prerequisites (quote_id and quote_hash from mcg_quote) and the recovery path for a stale/expired quote ('re-quote and retry'), plus the replay semantics for idempotency_key. It stops short of naming alternative siblings or stating when NOT to launch (e.g., cancel/observe via mcg_get_run), so it is clear context rather than full when/when-not guidance.

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