StellarMCP

stellar_submit_fee_bump_transaction

Sponsor transaction fees for a signed inner transaction by submitting a Fee Bump Transaction with a designated fee-paying account.

Instructions

Sponsor the fees for an existing transaction using a Fee Bump Transaction. Submits to the network.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "innerTxXdr": "<innerTxXdr>",
      "feeAccount": "<feeAccount>"
    },
    "name": "stellar_submit_fee_bump_transaction"
  }
}

Input Schema

Name	Required	Description
`innerTxXdr`	Yes	Base64 encoded inner transaction XDR (must be signed by the inner source account)
`feeAccount`	Yes	Account that will pay the fees (sponsor)
`maxFee`	No	Maximum fee to pay (in stroops). Defaults to a reasonable minimum.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.9Jun 25, 2026

TDQS

A3.5/5.0

Behavior3/5

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

With no annotations, the description must disclose side effects. It does state 'Submits to the network,' which makes the external network effect explicit and indicates fees will be sponsored. However, it does not describe consequences such as fee deduction, irreversibility, failure behavior, or whether the inner transaction is executed.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences with no filler; the key action and network-submission effect are front-loaded. It is an efficient description, though 'Fee Bump Transaction' slightly echoes the tool name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool has no annotations and no output schema, so the description must carry more context. It omits practical details such as what is returned after submission, whether the sponsor account must be funded, and what errors or prerequisites apply beyond those in the parameter schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description adds no parameter-level detail beyond the schema, but the schema already explains feeAccount and innerTxXdr clearly, including the signing requirement. maxFee is also documented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb and object: 'Sponsor the fees for an existing transaction using a Fee Bump Transaction.' This clearly identifies the action and resource, and distinguishes it from sibling payment/submission tools like stellar_submit_payment by emphasizing fee sponsorship rather than ordinary payment submission.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies the use case: when you already have a signed inner transaction and want a sponsor to pay its fees. However, it does not explicitly state when not to use this tool, nor does it name alternatives or conditions that would select a different submit path.

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