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

Annotations already declare readOnlyHint=false, idempotentHint=true, and destructiveHint=false, so the bar for added context is lower. The description adds genuinely useful behavior beyond annotations: no production secrets or credentials required, request_id must be reused on retries, and the expected polling window. No contradiction with annotations exists.

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 dense sentences with no filler: main action and flow variants first, then idempotency and polling instructions, then safety guidance. Every sentence earns its place and the most important operational details are front-loaded.

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?

Given there is no output schema, the description correctly tells the agent what to do after invocation: poll lunium_get_sandbox_demo after 3 seconds for up to 60 seconds. It also covers idempotency, the default flow, and the absence of real credential requirements, so an agent has everything needed to call and follow up 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 coverage is only 33%, but the description compensates well for two of the three parameters: it explains each flow enum value (cashin, custody, payout, cashout) and clarifies that request_id should be a random UUID reused on retries. lead_token still relies on its schema description, but that one is already clear in the schema. Overall, this is meaningful semantic enrichment beyond 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 ('Creates a test-only key and runs'), a concrete resource ('complete synthetic journey'), and enumerates the four available flow variants with their exact meanings. This clearly separates it from siblings like lunium_create_sandbox_key (key only) and lunium_get_sandbox_demo (polling the result).

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 makes clear this is for synthetic, test-only scenarios where no real funds or credentials are needed, and gives an explicit polling workflow: call lunium_get_sandbox_demo after 3 seconds for up to 60 seconds. It does not explicitly name alternatives or say 'use this instead of X', but the test-only framing and workflow are sufficient guidance.

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