xendit-mcp

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

No annotations are provided, so the description carries full burden for behavioral disclosure. The description mentions filtering capabilities but doesn't disclose important behavioral traits like whether this is a read-only operation, pagination behavior, rate limits, authentication requirements, or what the return format looks like. For a list tool with 6 parameters and no annotations, this leaves significant gaps in understanding how the tool behaves.

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 with just two sentences. The first sentence states the core functionality, and the second provides specific usage guidance. Every word earns its place, and the information is front-loaded with the primary purpose stated first.

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 the tool's moderate complexity (6 parameters, no output schema, no annotations), the description provides adequate but incomplete context. It covers the purpose and gives specific usage guidance but lacks behavioral transparency about how the tool operates, what it returns, and limitations. For a list tool with filtering capabilities, more complete context would include information about pagination, response format, and operational constraints.

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 83% (high), so the baseline is 3 even with minimal parameter info in the description. The description adds some value by explaining that external_id filtering is 'usually the CareNow loan ID' and mentioning the 'Wrong VA / Payment Discrepancy' use case, which provides context beyond the schema. However, it doesn't add significant semantic information for most parameters.

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 verb ('List') and resource ('invoices') with optional filtering, which is specific and actionable. However, it doesn't explicitly distinguish this tool from sibling tools like 'xendit_get_invoice' (singular) or 'xendit_list_transactions', leaving some ambiguity about when to use this versus other list tools.

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 clear context for when to use this tool: 'For Wrong VA / Payment Discrepancy, filter by external_id (usually the CareNow loan ID).' This gives a specific use case and guidance on parameter usage. However, it doesn't explicitly state when NOT to use it or mention alternatives among sibling tools, which would be needed for a perfect score.

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