dVeracity Semantic MCP server

Gives any MCP-capable AI agent (Claude Code, Cursor, custom agents) metered access to the dVeracity Semantic API — natural-language queries over the verified-emissions knowledge graph (Open Footprint / PPDM / OGMP-methane) — and VaaS standards validation.

Prerequisites

An api-tier subscription: https://dveracity.com/pricing
An API key (dvrc_…): POST /api/v1/api-keys (or the dashboard)
API credits for metered calls: POST /api/v1/vaas/credits/purchase

The machine-readable service contract lives at GET /api/v1/semantic/manifest (public, no auth).

Install

From this directory: npm install

Claude Code

claude mcp add dveracity \
  -e DVERACITY_API_KEY=dvrc_yourkey \
  -- node /path/to/dVE/mcp/semantic-mcp/index.js

Generic MCP JSON config (Cursor, etc.)

{
  "mcpServers": {
    "dveracity": {
      "command": "node",
      "args": ["/path/to/dVE/mcp/semantic-mcp/index.js"],
      "env": { "DVERACITY_API_KEY": "dvrc_yourkey" }
    }
  }
}

Optional: DVERACITY_API_URL overrides the API base URL (defaults to prod).

KERI mode — verified agent identity (optional)

If the agent holds a dVeracity Agent Authorization credential (an ACDC issued by its Legal Entity, chained to the Legal Entity's vLEI — see elm/docs/VLEI_AGENT_TOKENS_DESIGN.md), set:

DVERACITY_KERI_AID=<the agent's AID (credential issuee)>
DVERACITY_KERI_PRESENTATION=/path/to/agent-credential.cesr   # self-contained CESR

The server then authenticates the agent by verifiable presentation (challenge → exchange → 1-hour session, refreshed transparently) and attaches X-Keri-Session to every call: the API key keeps carrying billing, the KERI session adds verified identity — every metered call is attributed to the agent AID and Legal Entity LEI in dVeracity's audit trail. The keri_identity tool (free) shows the active identity. Scope denials (a credential that doesn't carry e.g. semantic:query) surface as actionable errors naming the carried scopes. Signify-based nonce signing is a planned enhancement.

Tools

Tool	Cost	What it does
`semantic_query`	credits	Natural-language question over the verified-emissions knowledge graph
`semantic_templates`	free	Catalog of supported query templates
`credits_balance`	free	Remaining credit balance
`list_standards`	free	Standards VaaS can validate against
`validate_data`	credits	Validate a payload against a supported standard
`keri_identity`	free	This agent's verified vLEI identity, when KERI mode is configured

Open Footprint canonical model

Design-time tools for building an application on the Open Footprint standard. Reading the model is free; only the check at the end is metered.

Tool	Cost	What it does
`ofp_models`	free	The eight model domains, and which database dialects have published DDL
`ofp_search_entities`	free	Search 239 canonical entities by name, description or field
`ofp_entity`	free	One entity in full: fields, types, keys, relationships, physical table
`ofp_sectors`	free	Industry sectors, each with a status
`ofp_sector`	free	One sector, with its reference artifacts
`ofp_policies`	free	A sector's Rego guardrails, or an explicit "none published"
`ofp_validate`	credits	Check a payload against the model and, optionally, sector guardrails
`ofp_semantics`	free	O-DEF semantic codes, for aligning another system's fields onto the model
`ofp_semantic_code`	free	Which canonical fields carry one code — the reverse lookup a connector needs
`ofp_model_provenance`	free	Which snapshot of the standard this deployment serves

Two behaviours are deliberate and worth knowing before you build against them.

Ambiguous entity names fail rather than resolve. 48 of the 239 entity names are defined in more than one domain — Country is in four. ofp_entity without a domain returns an error listing the candidates instead of picking one. Pass domain whenever you know it.

Semantic codes vary wildly in usefulness. 660 of 813 canonical fields carry an O-DEF code, but the distribution is skewed: one generic code covers 255 fields. Only about 16% sit on a code shared by ten fields or fewer. Every code is returned with its fieldCount — check it before aligning to one, and pass maxFieldCount: 10 to ofp_semantics to see only the precise ones.

"Nothing published" is an answer, not an error. Most sectors are named in the taxonomy but have no reference implementation, and only seven publish policy guardrails. ofp_policies on such a sector returns published: false with a reason, and ofp_validate reports policy.ran: false. Both mean no rules are published, never there are no constraints — a payload checked for structure alone is not a compliant one, and should not be described as one.

A fourth outcome, unevaluable, means the sector's rules ran but every rule that came back false reads an input the payload does not carry (policy.missingInputs, e.g. co2e_kg, direction, counterparty_industry). Those are e-ledger record fields, not canonical Open Footprint field names — ofp_policies lists them per policy under inputs. Unevaluable is neither a pass nor a breach, and valid is null.

Billing behavior (for agents)

Metered calls return an HTTP 402 when the account is out of credits. The server surfaces this as a tool error that tells the agent to ask its human operator to purchase credits or upgrade — agents should relay that message and stop, not retry.

Test

npm test (no network; the HTTP layer is stubbed).