check_balance

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

With no annotations provided, the description carries full burden for behavioral disclosure. It effectively communicates key behavioral traits: this is a read operation (implied by 'check'), it requires authentication ('Requires API key'), and it's specific to the402.ai platform. It doesn't mention rate limits, error conditions, or response format, but covers the essential safety and authentication context well for a simple tool.

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?

The description is perfectly concise and well-structured: two sentences that each earn their place. The first sentence states the core purpose, the second adds crucial context about usage and authentication requirements. There's zero wasted verbiage or redundancy.

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 zero-parameter tool with no annotations and no output schema, the description provides good contextual completeness. It explains what the tool does, what the balance represents, and authentication requirements. The main gap is the lack of information about return format or what the response contains, but given the tool's simplicity, this is a minor omission.

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 tool has zero parameters with 100% schema description coverage, so the baseline is 4. The description appropriately doesn't waste space discussing parameters that don't exist, which is efficient and correct. No additional parameter semantics are needed or provided.

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 states the tool's purpose: checking a pre-funded USDC balance on the402.ai platform. It specifies the resource (balance) and context (used for purchases, service inquiries, and other paid operations via MCP server). However, it doesn't explicitly differentiate from sibling tools like 'balance_history' or 'provider_earnings', which prevents a perfect score.

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 provides some usage context by stating the balance is used for purchases and paid operations, and mentions it requires an API key. However, it doesn't explicitly guide when to use this tool versus alternatives like 'balance_history' (which might show transaction history) or 'provider_earnings' (which might show earnings rather than balance). The guidance is implied rather than explicit.

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