Estimate the Lightning network fee before paying an open, no-amount bolt11 invoice by providing the wallet ID, payment request, and amount in satoshis.
Estimate the Lightning network fee for paying an open (no-amount) invoice
| Name | Required | Description | Default |
|---|---|---|---|
| amount | Yes | The amount you want to send in satoshis | |
| wallet_id | Yes | The wallet ID to pay from | |
| payment_request | Yes | The bolt11 payment request |
Changes observed during successful MCP inspections.
v2.0.0Input schema / properties / amount / exclusiveMinimumAdded value: +0Input schema / properties / amount / maximumAdded value: +9007199254740991Input schema / properties / amount / typePrevious value: -"number"New value: +"integer"v1.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full burden. 'Estimate' implies a read-only calculation with no funds moved, but the description never confirms there are no side effects, no wallet mutation, or what the estimate is derived from. It provides minimal behavioral context beyond the verb.
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?
A single, front-loaded sentence with no filler; every word contributes to scope. It is efficient but extremely terse, leaving no room for the clarifying detail that would help an agent.
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 3-required-parameter estimation tool with no annotations and no output schema, the description is thin. It doesn't explain the required amount-vs-no-amount relationship or the shape of the returned estimate, both of which an agent would benefit from.
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 all three parameters (amount, wallet_id, payment_request) are already documented in the schema. The description adds no parameter-level detail — notably it does not explain why 'amount' is required when the invoice has no amount.
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 gives a specific verb ('Estimate') and resource ('Lightning network fee') plus the qualifying condition 'open (no-amount) invoice', which implicitly separates it from the sibling estimate_lightning_fee. It stops short of naming that sibling, so the distinction must be inferred.
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 'open (no-amount) invoice' qualifier implies when this tool applies, but no alternative is named and no exclusion or prerequisite is stated. An agent must guess that estimate_lightning_fee covers amount-bearing invoices.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.