Sign a Stellar transaction envelope using a secret key, identity, or seed phrase, with optional network and HD path settings, so it can be submitted to the blockchain.
Sign a transaction envelope
| Name | Required | Description | Default |
|---|---|---|---|
| tx_xdr | Yes | Transaction XDR to sign (base64) | |
| hd_path | No | HD path if using seed phrase | |
| network | No | Stellar network | |
| sign_with_key | No | Key to sign with (identity, secret key, or seed phrase) |
Changes observed during successful MCP inspections.
v1.0.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It does not disclose that this is a signing/mutating cryptographic operation, which key sources are acceptable, whether it requires prior key setup, whether the result is returned or broadcast, or whether the operation is irreversible. Only the bare verb 'Sign' conveys 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?
A single four-word sentence with the verb and object front-loaded; nothing is wasted. It is arguably under-specified rather than verbose, but structurally it is clean and to the point.
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 4-parameter cryptographic tool with no annotations and no output schema, the description omits essential context: what the tool returns (signed XDR vs. broadcast result), whether a key/identity must already be configured, and how it relates to stellar_tx_send. The one-line description is not complete enough for an agent to invoke confidently in a workflow.
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 each of the four parameters documented in the schema (tx_xdr, hd_path, network enum, sign_with_key). The description adds nothing about parameter semantics, so the baseline 3 applies.
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?
States a specific verb (Sign) and resource (transaction envelope), which is unambiguous on its own. However it offers no differentiation from signing-adjacent siblings such as stellar_tx_send, stellar_tx_simulate, or stellar_tx_hash, so an agent cannot tell from this text alone where signing ends and sending begins.
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?
There is no guidance on when to use this tool versus alternatives, no prerequisites (e.g. a key must be configured), and no statement of whether a signed envelope is submitted or merely returned. Usage must be inferred entirely from the name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.