Hedera Toolbox

contract_call

Execute read-only calls to Hedera smart contract functions to query data without submitting transactions or paying gas fees. Returns contract function results using 0.5 HBAR per call.

Instructions

Execute a read-only call to a Hedera smart contract function and return the result. Does not submit a transaction or cost gas. Costs 0.5 HBAR.

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": {
      "api_key": "<api_key>",
      "contract_id": "<contract_id>",
      "function_name": "<function_name>"
    },
    "name": "contract_call"
  }
}

Input Schema

Name	Required	Description
`api_key`	Yes	Your HederaIntel API key
`contract_id`	Yes	Hedera contract ID (e.g. 0.0.123456) or EVM address (0x...)
`function_name`	Yes	Contract function name to call (e.g. balanceOf, totalSupply, name)
`function_params`	No	Optional array of parameter values to pass to the function
`abi_hint`	No	Optional ABI hint - common values: ERC20, ERC721, HTS

Schema Changelog

Changes observed during successful MCP inspections.

First observedv3.4.5Mar 18, 2026

TDQS

A4.2/5.0

Behavior4/5

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

With no annotations provided, the description carries full burden and effectively discloses key behavioral traits: it's read-only, non-transactional, gas-free, and specifies a cost ('Costs 0.5 HBAR'), which are crucial for an agent to understand operational constraints and implications.

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 with zero waste: the first states purpose and key behavior, the second adds cost information. It's front-loaded with essential details and appropriately sized for the tool's complexity.

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?

Given no annotations and no output schema, the description is mostly complete for a read-only contract call tool, covering purpose, behavior, and cost. However, it lacks details on error handling or response format, which could aid the agent in anticipating outcomes.

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 description coverage is 100%, so the baseline is 3. The description doesn't add meaning beyond the schema, such as explaining parameter interactions or usage examples, but doesn't need to compensate for gaps.

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 clearly states the specific action ('execute a read-only call'), target resource ('Hedera smart contract function'), and outcome ('return the result'), distinguishing it from siblings like contract_analyze or token_monitor that imply analysis rather than direct execution.

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?

It explicitly states when to use this tool ('read-only call... does not submit a transaction or cost gas') and distinguishes it from transactional calls, though it doesn't specify alternatives among siblings like contract_read or when not to use it for other purposes.

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