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Glama

🐴 Gulltoppr

by io.github.portdeveloper

Simulate a transaction

simulate
Read-only

Simulate a call and return success, gas, decoded return, and best-effort state diff / asset changes / logs. Provide a high-level call (address + function + args) or raw (to + data), never both.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
toNoRaw form: target address.
argsNoFunction arguments, in order. Pass uint values as decimal strings.
dataNoRaw form: calldata (0x-prefixed hex bytes).
fromYesThe sender address (the user's wallet). No key is needed — nothing is signed.
chainYesChain alias from GET /v1/chains (for example "ethereum", "base", "monad", "bsc") or numeric EIP-155 chain id.
valueNoNative value in wei (decimal string), for payable functions.
addressNo0x contract address.
rpc_urlNoOverride HTTP(S) RPC URL. Required for chains with no default (e.g. local/31337) or custom EVM chain ids.
functionNoFunction name, or full signature like "transfer(address,uint256)" if overloaded.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
logsYes
revertNo
successYes
gas_usedYes
state_diffYes
return_valueNo
asset_changesYes

Schema Changelog

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

  1. Changed15 schema fields changed
    • addedInput schema / properties / address / pattern
      Added value: +"^0x[0-9a-fA-F]{40}$"
    • addedInput schema / properties / chain / anyOf
      Added value: +[
+  {
+    "minLength": 1,
+    "type": "string"
+  },
+  {
+    "exclusiveMinimum": 0,
+    "type": "integer"
+  }
+]
    • changedInput schema / properties / chain / description
      Previous value: -"Chain alias (\"ethereum\", \"base\", \"optimism\", \"arbitrum\", \"polygon\", \"local\") or numeric chain id."New value: +"Chain alias from GET /v1/chains (for example \"ethereum\", \"base\", \"monad\", \"bsc\") or numeric EIP-155 chain id."
    • removedInput schema / properties / chain / type
      Removed value: -"string"
    • changedInput schema / properties / data / description
      Previous value: -"Raw form: calldata (0x…)."New value: +"Raw form: calldata (0x-prefixed hex bytes)."
    • addedInput schema / properties / data / pattern
      Added value: +"^0x([0-9a-fA-F]{2})*$"
    • addedInput schema / properties / from / pattern
      Added value: +"^0x[0-9a-fA-F]{40}$"
    • addedInput schema / properties / function / minLength
      Added value: +1
    • addedInput schema / properties / function / pattern
      Added value: +"\\S"
    • changedInput schema / properties / rpc_url / description
      Previous value: -"Override RPC URL. Required for chains with no default (e.g. local/31337)."New value: +"Override HTTP(S) RPC URL. Required for chains with no default (e.g. local/31337) or custom EVM chain ids."
    • addedInput schema / properties / rpc_url / pattern
      Added value: +"^https?:\\/\\/\\S+$"
    • addedInput schema / properties / to / $ref
      Added value: +"#/properties/address"
    • removedInput schema / properties / to / type
      Removed value: -"string"
    • addedInput schema / properties / value / pattern
      Added value: +"^\\d+$"
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "asset_changes": {
+      "items": {
+        "additionalProperties": true,
+        "properties": {
+          "address": {
+            "$ref": "#/properties/state_diff/items/properties/address"
+          },
+          "delta": {
+            "pattern": "^-?\\d+$",
+            "type": "string"
+          },
+          "kind": {
+            "enum": [
+              "erc20",
+              "erc721",
+              "erc1155",
+              "native"
+            ],
+            "type": "string"
+          },
+          "symbol": {
+            "type": "string"
+          },
+          "token": {
+            "$ref": "#/properties/state_diff/items/properties/address"
+          }
+        },
+        "required": [
+          "address",
+          "token",
+          "delta",
+          "kind"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "gas_used": {
+      "minimum": 0,
+      "type": "integer"
+    },
+    "logs": {
+      "items": {
+        "additionalProperties": true,
+        "properties": {
+          "address": {
+            "$ref": "#/properties/state_diff/items/properties/address"
+          },
+          "args": {
+            "additionalProperties": {},
+            "type": "object"
+          },
+          "event": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "address"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "return_value": {
+      "additionalProperties": true,
+      "properties": {
+        "decoded": {
+          "type": "array"
+        },
+        "raw": {
+          "description": "Raw form: calldata (0x-prefixed hex bytes).",
+          "pattern": "^0x([0-9a-fA-F]{2})*$",
+          "type": "string"
+        }
+      },
+      "required": [
+        "decoded",
+        "raw"
+      ],
+      "type": "object"
+    },
+    "revert": {
+      "additionalProperties": true,
+      "properties": {
+        "decoded": {
+          "type": "string"
+        },
+        "reason": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "reason"
+      ],
+      "type": "object"
+    },
+    "state_diff": {
+      "items": {
+        "additionalProperties": true,
+        "properties": {
+          "address": {
+            "description": "0x contract address.",
+            "pattern": "^0x[0-9a-fA-F]{40}$",
+            "type": "string"
+          },
+          "after": {
+            "type": "string"
+          },
+          "before": {
+            "type": "string"
+          },
+          "slot_label": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "address",
+          "before",
+          "after"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "success": {
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "success",
+    "gas_used",
+    "state_diff",
+    "asset_changes",
+    "logs"
+  ],
+  "type": "object"
+}
  2. First observed

TDQS

A4.7/5.0
Behavior5/5

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

Description adds behavioral details beyond readOnlyHint and openWorldHint annotations: discloses return values and notes state diff is 'best-effort'. No contradiction with annotations; simulation is read-only and open-world.

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 sentences: first states purpose and return, second provides usage guidance. Extremely concise with no redundant information.

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

Completeness5/5

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

Given output schema exists, description sufficiently covers return types and input constraints for a 9-parameter simulation tool. No missing critical details.

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

Parameters4/5

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

Schema coverage is 100%, and parameter descriptions are clear (e.g., 'no key needed' for from). Description adds value by grouping high-level vs raw parameters and enforcing 'never both' 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?

Description clearly states the tool simulates a call and returns success, gas, decoded return, state diff, asset changes, and logs. It distinguishes high-level vs raw input forms, setting it apart from sibling tools like read_contract or prepare_tx.

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?

Description provides explicit rule 'never both' for high-level vs raw forms. While it doesn't directly compare with alternatives, the return type implies simulation use case. Could be stronger with when-not scenarios.

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.

Resources