ZEAM :: Prism

Call a JSON-RPC method

call_rpc

Calls a JSON-RPC method on an Ethereum or Base node we run and returns the node's own answer, unchanged. Base serves eth_, net_, web3_, txpool_, debug_ and base_ methods; Ethereum serves eth_, net_, web3_, txpool_, debug_ and trace_ methods. The full list is in /llms.txt, checked against the nodes every hour. Base is archive: state at any block. Ethereum is archive: state at any block. Base "pending" is the next block as it builds, updated about every 200 ms (Flashblocks): eth_getBlockByNumber ["pending", true]. To stream, open the websocket at /rpc/?line= and eth_subscribe. Base: newHeads, logs, syncing, newFlashblocks, pendingLogs, newFlashblockTransactions. Ethereum: newHeads, logs, newPendingTransactions, syncing. Send with eth_sendRawTransaction. The node holds no keys, so signing methods are refused. Paid: $0.000001 per millisecond on a line, or $0.00025 for a call of up to 250 ms without one. With no wallet code, pay with ZEAM :: Pass: a pass (https://mcp.zeamprism.com/pass) or your own wallet (https://mcp.zeamprism.com/how-to-pay). Example: {"chain":"base","method":"eth_blockNumber","params":[]}

Input Schema

Name	Required	Description
`line`	No	Optional. A line credential, for a client that cannot send the x-line header or _meta["zeam-pass/line"]: the call runs on that line's time.
`chain`	Yes	string — which node to forward to: eth or base
`method`	Yes	string — a JSON-RPC method; the ones we check are listed in /llms.txt. Not forwarded: signing methods, debug_ methods that control the node, eth_subscribe (use the websocket).
`params`	No	optional array — JSON-RPC params, default []

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed8 schema fields changedOct 15, 2026

removedInput schema / $schema

Removed value: -"https://json-schema.org/draft/2020-12/schema"

addedInput schema / examples

Added value: +[
+  {
+    "chain": "base",
+    "method": "eth_blockNumber",
+    "params": []
+  }
+]

changedInput schema / properties / line / description

Previous value: -"optional — a line credential: the call burns the line's time and carries no payment."New value: +"Optional. A line credential, for a client that cannot send the x-line header or _meta[\"zeam-pass/line\"]: the call runs on that line's time."

removedInput schema / properties / params / items
```
Removed value: -{}
```

removedOutput schema / $schema

Removed value: -"https://json-schema.org/draft/2020-12/schema"

removedOutput schema / additionalProperties
```
Removed value: -{}
```

addedOutput schema / anyOf

Added value: +[
+  {
+    "properties": {
+      "chain": {
+        "anyOf": [
+          {
+            "description": "the node this was forwarded to",
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      },
+      "http_status": {
+        "anyOf": [
+          {
+            "description": "the node's HTTP status",
+            "type": "number"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      },
+      "method": {
+        "anyOf": [
+          {
+            "description": "the JSON-RPC method called",
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      },
+      "rpc_response": {
+        "anyOf": [
+          {
+            "description": "the node's JSON-RPC envelope, verbatim",
+            "properties": {},
+            "type": "object"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      }
+    },
+    "type": "object"
+  },
+  {
+    "required": [
+      "error"
+    ],
+    "type": "object"
+  },
+  {
+    "required": [
+      "accepts"
+    ],
+    "type": "object"
+  },
+  {
+    "required": [
+      "receipt"
+    ],
+    "type": "object"
+  }
+]

removedOutput schema / properties

Removed value: -{
-  "chain": {
-    "anyOf": [
-      {
-        "description": "the node this was forwarded to",
-        "type": "string"
-      },
-      {
-        "type": "null"
-      }
-    ]
-  },
-  "http_status": {
-    "anyOf": [
-      {
-        "description": "the node's HTTP status",
-        "type": "number"
-      },
-      {
-        "type": "null"
-      }
-    ]
-  },
-  "method": {
-    "anyOf": [
-      {
-        "description": "the JSON-RPC method called",
-        "type": "string"
-      },
-      {
-        "type": "null"
-      }
-    ]
-  },
-  "rpc_response": {
-    "anyOf": [
-      {
-        "additionalProperties": {},
-        "description": "the node's JSON-RPC envelope, verbatim",
-        "properties": {},
-        "type": "object"
-      },
-      {
-        "type": "null"
-      }
-    ]
-  }
-}

Changed2 schema fields changedOct 6, 2026

addedInput schema / properties / chain / enum
```
Added value: +[
+  "base",
+  "eth"
+]
```

changedInput schema / properties / method / description

Previous value: -"string — a method from the list in /llms.txt. Not forwarded: signing methods, debug_ methods that control the node, eth_subscribe (use the websocket)."New value: +"string — a JSON-RPC method; the ones we check are listed in /llms.txt. Not forwarded: signing methods, debug_ methods that control the node, eth_subscribe (use the websocket)."

Changed1 schema field changedOct 5, 2026

changedInput schema / properties / method / description

Previous value: -"string — any eth_, net_, web3_, txpool_, debug_, base_ method the node serves, and trace_ on eth. Not forwarded: signing methods, debug_ methods that control the node, eth_subscribe (use the websocket)."New value: +"string — a method from the list in /llms.txt. Not forwarded: signing methods, debug_ methods that control the node, eth_subscribe (use the websocket)."

Changed1 schema field changedOct 5, 2026

changedInput schema / properties / method / description

Previous value: -"string — any method the node serves: eth_*, net_*, web3_*, txpool_*, debug_*, trace_*; admin_/personal_/miner_/engine_ refused."New value: +"string — any eth_, net_, web3_, txpool_, debug_, base_ method the node serves, and trace_ on eth. Not forwarded: signing methods, debug_ methods that control the node, eth_subscribe (use the websocket)."

Changed1 schema field changedOct 1, 2026

changedInput schema / properties / line / description

Previous value: -"optional — your /pay credential: served off your line, no payment; without it, x402 payment in params._meta."New value: +"optional — a line credential: the call burns the line's time and carries no payment."

AddedSep 18, 2026

TDQS

A4.1/5.0

Behavior4/5

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

Annotations mark this as non-read-only and open-world, and the description adds substantial context beyond them: unchanged node answers, archive state on both chains, pending/Flashblocks cadence, no key custody, and refused method classes. It does not explicitly name eth_sendRawTransaction as a state-mutating call the readOnlyHint=false annotation implies, but the overall transparency is high.

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?

The core purpose is front-loaded and each block covers a distinct concern. It is long, but most sentences carry operational detail an agent needs for a low-level RPC passthrough with payment and streaming behavior.

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?

For a high-complexity open-world RPC tool, the description covers chain/method scope, streaming alternative, signing refusal, archive and pending semantics, payment mechanics, and a call example. With an output schema present, return-value explanation is unnecessary, leaving no material gap.

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?

With 100% schema coverage, the baseline is 3. The description adds real value with a concrete call example and the pending-block params example, and explains how chain selection changes the available method families.

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

Purpose4/5

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

States a specific verb and resource: calls a JSON-RPC method on an Ethereum or Base node and returns the node's answer unchanged. The chain and method scope make the tool's remit unmistakable, though it never distinguishes itself from the sibling sample_rpc, so it falls short of a 5.

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?

Gives explicit routing: use the websocket for eth_subscribe, send transactions via eth_sendRawTransaction, and signing methods are refused. That is strong when/when-not guidance, but the sibling sample_rpc is never mentioned, leaving one alternative unresolved.

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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