xendit-mcp

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 mentions that the tool 'Returns a payment link your customer can use to pay,' which adds some context about output behavior. However, it lacks critical details: whether this is a mutating operation (implied by 'create'), error conditions, rate limits, authentication requirements, or what happens on failure. For a creation tool with zero annotation coverage, this is insufficient.

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: two sentences that directly state the tool's action and key output. Every word earns its place, with no redundancy or fluff. It's front-loaded with the primary purpose ('Create a new payment invoice').

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 complexity (creation operation with 6 parameters) and lack of both annotations and output schema, the description is incomplete. It doesn't cover behavioral aspects like mutation effects, error handling, or authentication needs. While it mentions the return includes a payment link, it doesn't describe the full response structure or success/failure conditions. For a creation tool, this leaves significant gaps for the agent.

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%, so the schema fully documents all parameters. The description adds no additional parameter semantics beyond what's in the schema (e.g., it doesn't explain relationships between parameters or provide examples). The baseline score of 3 reflects adequate coverage solely from the schema, with no extra value from the description.

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: 'Create a new payment invoice' (verb+resource). It distinguishes from siblings like 'get_invoice' or 'expire_invoice' by focusing on creation. However, it doesn't explicitly differentiate from 'create_disbursement' which is another creation tool, preventing 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 no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., authentication needs), compare with 'create_disbursement' for different payment flows, or specify scenarios where this is appropriate. The agent must infer usage from the tool name alone.

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