Cross-LLM MCP Server

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 but offers minimal information. It states 'Pay a Lightning invoice' but doesn't clarify critical traits: whether this is a destructive/mutative operation (likely yes, but not stated), authentication requirements, rate limits, error conditions, or what happens upon success (e.g., funds deducted, invoice marked paid). This leaves significant gaps for an agent to understand the tool's behavior.

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 a single, clear sentence with zero wasted words. It is appropriately sized for a simple tool with one parameter and is front-loaded with the core action. Every part of the sentence earns its place by directly stating the tool's purpose.

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 complexity (a payment operation likely involving financial transactions), lack of annotations, and no output schema, the description is incomplete. It doesn't address key contextual aspects: what the tool returns (e.g., payment status, transaction ID), error handling, security implications, or dependencies. For a tool that could have significant side effects, this minimal description is insufficient.

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 input schema has 100% description coverage, with the 'invoice' parameter documented as 'BOLT11 Lightning invoice'. The description adds no additional parameter semantics beyond this, as it doesn't explain format details, validation, or examples. According to scoring rules, with high schema coverage (>80%), the baseline is 3 even without param info in 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 action ('Pay') and the resource ('a Lightning invoice'), making the purpose immediately understandable. It distinguishes from siblings like decode_invoice or validate_address by specifying a payment action rather than analysis/validation. However, it doesn't specify what 'pay' entails operationally (e.g., sending funds, marking as paid), keeping it from 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., needing a funded wallet), exclusions (e.g., not for on-chain payments), or comparisons to sibling tools like decode_invoice (which might be used first to inspect an invoice). Usage is implied only by the tool name and purpose.

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