Rubric Protocol MCP Server

hedera_fact

Fetch a $0.001 USDC attested Hedera network fact—exchange rate, gas fees, supply, nodes, throughput, or topic state—and return the snapshot attestation ID for verifiable records.

Instructions

PAID ($0.001 USDC): one attested Hedera network fact (exchange-rate, gas-fees, supply, nodes, throughput, topic-state) with the attestation ID of the served snapshot.

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": {
      "fact": "<fact>"
    },
    "name": "hedera_fact"
  }
}

Input Schema

Name	Required	Description	Default
`fact`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.2.4Nov 9, 2026

TDQS

B3.2/5.0

Behavior3/5

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

With no annotations, the description carries the full burden, and it does disclose two genuinely useful traits: the tool is paid ($0.001 USDC) and each call returns a single fact plus the attestation ID of the served snapshot. It does not cover what happens on payment failure, whether an account/auth setup is required, whether calls are rate-limited, or whether results are cached/repeatable.

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?

One tightly packed sentence with the most decision-relevant information (paid, price) front-loaded. The parenthetical repeats the schema enum verbatim, which is mild waste but aids scanning.

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 simple one-enum-parameter lookup with no output schema, the description covers cost, scope, and the salient return element (attestation ID). Missing only edge-case behavior (payment failure, error modes), which is modest for a read-style facts tool.

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 0%, but the single parameter is a fully self-documenting enum, so the schema already conveys the valid values. The description only restates that enum list; its one real addition is the implicit 'one fact per call' constraint via the singular 'one attested ... fact'.

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 clear verb+resource: returns one attested Hedera network fact, with the eligible fact types enumerated. It is distinguishable from siblings like attest (which presumably creates attestations) and verify/get_proof, though it never explicitly contrasts itself with them.

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

Usage Guidelines2/5

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

No statement of when to use this versus alternatives such as get_proof, attest, or cost_estimate. The '$0.001 USDC' price tag implies a cost/benefit decision the agent should weigh, but the description offers no guidance on when that tradeoff is warranted or when a free sibling suffices.

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

Deploy Server