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Hedera Toolbox

by com.hederatoolbox.api

hcs_write_record

Destructive

Write a tamper-evident record to any open HCS topic on Hedera. Use this to write entries to your agent's own topic for continuity, memory, or history. topic_id is required — pass your agent topic ID. Optionally sign the record with your Fixatum DID key by passing agent_did and agent_signature together, which marks the record agent_signed instead of platform_witnessed. Returns record ID and tx proof. 0.1 HBAR.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
dataYesThe compliance data to record (any JSON object)
api_keyYesYour HederaIntel API key
topic_idYesHCS topic ID to write the record to. Must be an open topic you own or have access to.
agent_didNoOptional. Your Fixatum DID (did:hedera:mainnet:z{BASE58_PUBKEY}_{ACCOUNT_ID}). Must be passed together with agent_signature.
entity_idYesID of the entity this record relates to
record_typeYesType of compliance record (e.g. transaction, approval, audit_event)
agent_signatureNoOptional. Base64 Ed25519 signature over the canonical JSON of {topic_id, record_type, entity_id, data} with object keys sorted at every depth. Must be passed together with agent_did. A signature that does not match is rejected and the call is not charged.

Schema Changelog

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

  1. Changed2 schema fields changed
    • addedInput schema / properties / agent_did
      Added value: +{
+  "description": "Optional. Your Fixatum DID (did:hedera:mainnet:z{BASE58_PUBKEY}_{ACCOUNT_ID}). Must be passed together with agent_signature.",
+  "type": "string"
+}
    • addedInput schema / properties / agent_signature
      Added value: +{
+  "description": "Optional. Base64 Ed25519 signature over the canonical JSON of {topic_id, record_type, entity_id, data} with object keys sorted at every depth. Must be passed together with agent_did. A signature that does not match is rejected and the call is not charged.",
+  "type": "string"
+}
  2. Changed2 schema fields changed
    • changedInput schema / properties / topic_id / description
      Previous value: -"HCS topic ID to write the record to. Defaults to the HederaIntel platform topic."New value: +"HCS topic ID to write the record to. Must be an open topic you own or have access to."
    • changedInput schema / required
      Previous value: -[
-  "record_type",
-  "entity_id",
-  "data",
-  "api_key"
-]New value: +[
+  "topic_id",
+  "record_type",
+  "entity_id",
+  "data",
+  "api_key"
+]
  3. First observed

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already signal readOnlyHint=false and destructiveHint=true, and the description adds meaningful behavioral detail: records are tamper-evident, cost 0.1 HBAR, produce a record ID and tx proof, and can be marked agent_signed vs platform_witnessed. This goes beyond what annotations alone convey.

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?

The description is compact and front-loaded with the core purpose, followed by practical usage notes, optional signing behavior, return value, and cost. Every sentence adds useful information and none is redundant with the schema.

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 write tool with no output schema and 7 parameters, the description covers the key operational context: purpose, required topic, signing option, return output, and cost. It does not explicitly mention all access prerequisites, but the schema covers the 'open topic you own or have access to' constraint.

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?

The schema documents all parameters with 100% coverage, so the baseline is 3. The description adds a little value by explaining the paired agent_did/agent_signature behavior and what agent_signed vs platform_witnessed means, but it mostly restates what the schema already specifies.

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 names a concrete action ('Write a tamper-evident record'), a specific resource ('HCS topic on Hedera'), and its intended use ('continuity, memory, or history'). It clearly differentiates the write operation from sibling read/query/monitor tools like hcs_query and hcs_monitor.

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?

The description gives clear context: use it to write to your agent's own topic for continuity, memory, or history, and states that topic_id is required. It does not explicitly list exclusions or name alternative tools for when not to use it, but the intent is unambiguous.

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

A3.7/5.0
Disambiguation5/5

Each tool targets a distinct resource and action (e.g., contract read vs. contract call vs. contract analyze; hcs monitor vs. hcs query vs. hcs understand). Even within closely related groups, descriptions clearly differentiate the specific purpose, so an agent is unlikely to select the wrong tool.

Naming Consistency4/5

Most tools follow a domain_action pattern (e.g., contract_analyze, token_monitor, hcs_verify_record), but some are verb_noun (get_terms, confirm_terms) and a few are noun_noun (account_info, token_price, fixatum_score). While not perfectly uniform, the prefixes make the intended domain clear and the overall structure is readable.

Tool Count3/5

With 25 tools, the server is on the heavy end of the typical MCP scope. While each tool serves a specific niche across multiple Hedera domains (contracts, HCS, tokens, identity, governance, Fixatum), the sheer number could increase selection complexity, but it remains within the borderline range rather than being excessive.

Completeness4/5

The server covers a broad range of read/analyze operations across major Hedera areas, plus essential write/verification capabilities (hcs_write_record, hcs_verify_record) and an onboarding flow (get_terms, confirm_terms). Minor gaps exist, such as no token transfer history or unregister/update for Fixatum, but the core analytical purpose is well covered.

Resources