StellarMCP

stellar_xdr_guess

Decode a base64 XDR value and determine which Stellar XDR type successfully decodes it. Returns a single matching type.

Instructions

Given base64 XDR, return which XDR types decode successfully (single value only; not streams).

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": {
      "xdr": "<xdr>"
    },
    "name": "stellar_xdr_guess"
  }
}

Input Schema

Name	Required	Description	Default
`xdr`	Yes	Single XDR value as standard base64 (no data: URL prefix)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.9Jun 25, 2026

TDQS

A3.8/5.0

Behavior3/5

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

With no annotations, the description must carry behavioral disclosure. It states the core transform (base64 in → successful types out) and a limitation (not streams), which is transparent. It does not specify the return format, whether all matching types are returned or just the first, or behavior on invalid base64.

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

Conciseness5/5

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

One sentence, 14 words, no fluff. The action, input, and core constraint are front-loaded and every clause earns its place.

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

Completeness4/5

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

For a one-parameter tool with no annotations and no output schema, the description gives the input format and the high-level return concept. Missing the exact return shape (e.g., array of type names) and error behavior, but the tool's simplicity makes this a minor gap.

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 coverage is 100%, so the schema already documents the xdr parameter as a single base64 value without a data URL prefix. The description's 'single value only; not streams' reinforces the schema but adds no new semantic information beyond emphasizing the constraint.

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?

States a specific action: given base64 XDR, return which XDR types decode successfully. The 'single value only; not streams' clarifies scope, distinguishing it from any stream-oriented sibling. It also separates it from stellar_decode_xdr, which likely decodes to a known type.

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?

Provides a clear input constraint ('single value only; not streams') but no explicit when-to-use versus alternatives. An agent can infer it is for unknown XDR types, but there is no mention of using stellar_decode_xdr when the type is already known. No exclusion of alternatives beyond streams.

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