gateway_balance

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

With no annotations, the description carries the behavioral burden and does meaningful work: it discloses that the operation reads a current balance, specifies USDC base units, and states the required private key. It does not explicitly say the call is read-only, but the wording strongly implies a non-mutating balance lookup.

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?

Two compact sentences with no filler: the first states the tool's purpose and its relationship to nanopayments, and the second packs in unit semantics and an authentication requirement. Every sentence 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?

For a one-optional-parameter read tool, the description covers purpose, units, and auth. However, because there is no output schema, it does not specify the exact response shape or field name, and it does not address edge cases like an invalid key or missing gateway balance.

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?

The only parameter, rpc_url, is fully documented in the schema with its type and default value, so schema coverage is 100%. The description adds no parameter-specific detail, which aligns with the baseline score for high schema coverage.

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 clearly identifies the tool as reporting the buyer's current balance inside Circle Gateway on Arc and notes this is the balance nanopayments draw against. It distinguishes itself from deposit_to_gateway and proof-flow siblings, though it lacks an explicit imperative verb like 'get' or 'fetch'.

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?

Usage is implied: call this when you need the current balance that nanopayments draw against. It also states a prerequisite (PAYMENT_PRIVATE_KEY), but it never explicitly says when to use this instead of deposit_to_gateway or other alternatives, nor provides exclusions.

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