Cross-LLM MCP Server

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. It states the action ('decode') but doesn't explain what the decoding entails - whether it returns structured data like amount, destination, expiry, or just validation status. It also doesn't mention error conditions, rate limits, or authentication requirements, leaving significant gaps in understanding 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 extremely concise - a single sentence that directly states the tool's function without any unnecessary words. It's front-loaded with the core purpose and wastes no space on redundant information.

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 tool with no annotations and no output schema, the description is insufficiently complete. It doesn't explain what the decoding operation returns, what format the output takes, or what information can be extracted from the invoice. Given the complexity of Lightning invoices and the lack of structured output documentation, more context about the decoding results is needed.

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% with the single parameter 'invoice' well-documented as 'BOLT11 Lightning invoice'. The description adds no additional parameter semantics beyond what the schema provides, but since the schema does the heavy lifting with complete coverage, the baseline score of 3 is appropriate.

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 ('decode') and resource ('a Lightning invoice'), making the purpose immediately understandable. However, it doesn't differentiate this tool from its sibling 'decode_tx' which might handle similar decoding operations for different data types, nor does it specify what kind of information the decoding reveals.

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. With siblings like 'decode_tx' (decode transaction) and 'pay_invoice', there's no indication whether this tool should be used for analysis before payment, for validation, or for extracting payment details. No context about prerequisites or exclusions is mentioned.

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