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

Beyond the annotations (destructive/non-idempotent/openWorld), it discloses economically meaningful behavior: real traffic hits the user's site, Fuel is consumed when an estimate exists, refusals burn no Fuel and carry a reason, launchBlockers cause refusal with a list, and a timeout leaves launch state ambiguous so list_load_tests must be checked. That last point is exactly the context a non-idempotent tool needs. It also describes the return payload (id, stage, Dashboard link).

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-loaded with the core action and the approval prerequisite, then moves to failure modes and follow-up tools in a logical order. It runs long and repeats the refusal theme twice ('the refusal gives the reason' and 'a refusal carries their message'), which is minor waste but not enough to obscure the instructions.

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 destructive, non-idempotent, open-world call with no output schema, the description covers preconditions (approval, Fuel reporting, launchBlockers), failure and timeout handling, and explicitly describes the result fields and the follow-up tools (get_load_test_status, stop_load_test). Nothing an agent needs to invoke it safely is 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 only 33% — label is documented in the schema, but projectId and scenarioId have no descriptions there. The description implicitly frames scenarioId as a saved Scenario read via get_scenario and projectId as its owning project, but never states that explicitly or discusses the optional label, so the coverage gap is only partially compensated.

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 a saved Scenario as a Load Test, exactly as stored') and immediately distinguishes itself from creation/query siblings by noting the scenario must already exist and be read via get_scenario first. An agent can tell this apart from create_scenario, create_monitor or get_load_test_status 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?

Explicitly prescribes the sequence: read with get_scenario, report the Fuel estimate range and fuelBalance to the user, and launch only with approval. It also gives alternatives for edge cases — launch from the Dashboard when the plan refuses, and check list_load_tests before retrying after a timeout.

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