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

Annotations already cover read-only/idempotent/non-destructive, but the description adds substantial unique context: the $0.005 USDC x402 cost, the double-charge avoidance rule for the follow-up call, the returned fields, and the 'nothing is stored' / no-warranty disclaimer. This is behavior beyond what any structured field provides.

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 follow-up rule before the disclaimer. The warranty boilerplate ('Provided as is, with no warranty or guarantee of accuracy or fitness') is marginal, but the rest is dense and 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?

No output schema exists, yet the description enumerates the return fields (well id, origin, tool, price_usd, mcp URL, why), states the cost, and describes the required follow-up call. Nothing an agent needs to call and act on this tool 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 description coverage is 100% with a single fully documented 'need' parameter including examples, so the baseline of 3 applies. The description adds no meaning to the parameter itself 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 and resource — 'Keyword-route a natural-language need to the best Rainmaker well' — and names the sibling it is not ('Free alternative: list-wells'). An agent can distinguish this from list-wells and catalog-url 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 follow-up routing ('After recommend, open that origin's /mcp directly — gateway does not proxy') and an alternative with its selection condition ('Free alternative: list-wells'). The when-to-use and post-call workflow are both spelled out.

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