🐴 Gulltoppr

Explain a transaction

decode_tx

Read-only

Decode what a transaction did: delegated heimdall decode plus decoded_call from the resolved target ABI when available. Prefer decoded_call for typed function/arg names, and read its provenance.

Input Schema

TableJSON Schema

Name	Required	Description
`chain`	Yes	Chain alias from GET /v1/chains (for example "ethereum", "base", "monad", "bsc") or numeric EIP-155 chain id.
`rpc_url`	No	Override HTTP(S) RPC URL. Required for chains with no default (e.g. local/31337) or custom EVM chain ids.
`tx_hash`	Yes	0x transaction hash.

Output Schema

TableJSON Schema

Name	Required	Description
`chain`	Yes
`cached`	Yes
`source`	Yes
`decoded`	Yes
`tx_hash`	Yes	0x transaction hash.
`provenance`	Yes
`decoded_call`	No

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

Changed8 schema fields changedJul 28, 2026

addedInput schema / properties / chain / anyOf

Added value: +[
+  {
+    "minLength": 1,
+    "type": "string"
+  },
+  {
+    "exclusiveMinimum": 0,
+    "type": "integer"
+  }
+]

changedInput schema / properties / chain / description

Previous value: -"Chain alias (\"ethereum\", \"base\", \"optimism\", \"arbitrum\", \"polygon\", \"local\") or numeric chain id."New value: +"Chain alias from GET /v1/chains (for example \"ethereum\", \"base\", \"monad\", \"bsc\") or numeric EIP-155 chain id."

removedInput schema / properties / chain / type
```
Removed value: -"string"
```

changedInput schema / properties / rpc_url / description

Previous value: -"Override RPC URL. Required for chains with no default (e.g. local/31337)."New value: +"Override HTTP(S) RPC URL. Required for chains with no default (e.g. local/31337) or custom EVM chain ids."

addedInput schema / properties / rpc_url / pattern
```
Added value: +"^https?:\\/\\/\\S+$"
```

changedInput schema / properties / tx_hash / description

Previous value: -"0x… transaction hash."New value: +"0x transaction hash."

addedInput schema / properties / tx_hash / pattern
```
Added value: +"^0x[0-9a-fA-F]{64}$"
```

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "cached": {
+      "type": "boolean"
+    },
+    "chain": {
+      "type": "integer"
+    },
+    "decoded": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "type": "number"
+        },
+        {
+          "type": "boolean"
+        },
+        {
+          "type": "array"
+        },
+        {
+          "additionalProperties": {},
+          "type": "object"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "decoded_call": {
+      "anyOf": [
+        {
+          "additionalProperties": true,
+          "properties": {
+            "abi_for": {
+              "$ref": "#/properties/decoded_call/anyOf/0/properties/to"
+            },
+            "args": {
+              "items": {
+                "additionalProperties": true,
+                "properties": {
+                  "name": {
+                    "type": "string"
+                  },
+                  "type": {
+                    "type": "string"
+                  },
+                  "value": {
+                    "$ref": "#/properties/decoded"
+                  }
+                },
+                "required": [
+                  "name",
+                  "type",
+                  "value"
+                ],
+                "type": "object"
+              },
+              "type": "array"
+            },
+            "function": {
+              "type": "string"
+            },
+            "provenance": {
+              "additionalProperties": true,
+              "properties": {
+                "bytecode_match": {
+                  "additionalProperties": true,
+                  "properties": {
+                    "address": {
+                      "$ref": "#/properties/decoded_call/anyOf/0/properties/to"
+                    },
+                    "chain": {
+                      "type": "integer"
+                    },
+                    "confidence": {
+                      "$ref": "#/properties/decoded_call/anyOf/0/properties/provenance/properties/confidence"
+                    },
+                    "source": {
+                      "$ref": "#/properties/decoded_call/anyOf/0/properties/provenance/properties/source"
+                    }
+                  },
+                  "required": [
+                    "chain",
+                    "address",
+                    "source",
+                    "confidence"
+                  ],
+                  "type": "object"
+                },
+                "confidence": {
+                  "enum": [
+                    "verified",
+                    "partial",
+                    "decompiled",
+                    "selector-only"
+                  ],
+                  "type": "string"
+                },
+                "names_synthetic": {
+                  "type": "boolean"
+                },
+                "natspec": {
+                  "type": "boolean"
+                },
+                "notes": {
+                  "type": "string"
+                },
+                "source": {
+                  "enum": [
+                    "etherscan",
+                    "sourcify",
+                    "proxy-impl",
+                    "bytecode-match",
+                    "heimdall-decompiled",
+                    "4byte"
+                  ],
+                  "type": "string"
+                },
+                "verified": {
+                  "type": "boolean"
+                }
+              },
+              "required": [
+                "source",
+                "confidence",
+                "verified",
+                "names_synthetic",
+                "natspec"
+              ],
+              "type": "object"
+            },
+            "signature": {
+              "type": "string"
+            },
+            "to": {
+              "description": "0x contract address.",
+              "pattern": "^0x[0-9a-fA-F]{40}$",
+              "type": "string"
+            }
+          },
+          "required": [
+            "to",
+            "function",
+            "signature",
+            "args",
+            "abi_for",
+            "provenance"
+          ],
+          "type": "object"
+        },
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "provenance": {
+      "additionalProperties": true,
+      "properties": {
+        "confidence": {
+          "const": "decompiled",
+          "type": "string"
+        },
+        "names_synthetic": {
+          "const": true,
+          "type": "boolean"
+        },
+        "source": {
+          "type": "string"
+        },
+        "verified": {
+          "const": false,
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "source",
+        "confidence",
+        "verified",
+        "names_synthetic"
+      ],
+      "type": "object"
+    },
+    "source": {
+      "type": "string"
+    },
+    "tx_hash": {
+      "description": "0x transaction hash.",
+      "pattern": "^0x[0-9a-fA-F]{64}$",
+      "type": "string"
+    }
+  },
+  "required": [
+    "chain",
+    "tx_hash",
+    "source",
+    "cached",
+    "decoded",
+    "provenance"
+  ],
+  "type": "object"
+}

First observedJun 10, 2026

TDQS

A4.2/5.0

Behavior4/5

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

Adds value beyond annotations by detailing the dual decoding approach and provenance, though readOnlyHint already signals safety. No contradictions.

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?

Two concise sentences with front-loaded core function and actionable guidance. No wasted words.

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?

Covers key behavioral traits and output differentiation, and output schema handles return details. Minor gap: no mention of RPC override necessity, though schema covers it.

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 description adds no new parameter details. It mentions output preferences but not input specifics, meeting baseline with no degradation or improvement.

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 precisely states the tool decodes a transaction using heimdall decode and decoded_call from ABI. It clearly distinguishes from siblings like encode_call or simulate by focusing on decoding transactions.

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

Usage Guidelines4/5

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

Provides guidance to prefer decoded_call for typed names and to read provenance, but lacks explicit when-not-to-use compared to sibling tools like simulate or read_contract.

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

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TDQS

A4.4/5.0

Disambiguation5/5

Each tool has a clearly distinct purpose: decode vs encode, prepare vs simulate, resolve ABI vs selector, etc. No two tools overlap in functionality.

Naming Consistency5/5

All tool names follow a consistent verb_noun pattern with lowercase and underscores (e.g., decode_tx, list_chains, resolve_abi, runtime_metrics). The only exception is 'simulate', which is a single verb but still clear and consistent with the style.

Tool Count5/5

12 tools is an ideal count for a blockchain interaction server. Each tool covers a necessary step in the workflow without being overwhelming or sparse.

Completeness5/5

The tool set covers the full lifecycle of contract interaction: resolve ABI, encode/decode, simulate, prepare unsigned transactions, look up selectors, resolve names, and list chains. No obvious gaps given the server's purpose of preparing actions for external signing.

Explain a transaction

Input Schema

Output Schema

Schema Changelog

TDQS

Glama MCP Gateway

TDQS

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