# x402 and ERC-8004 protocol reference — Protocol Ledger

Canonical: https://protocol.agiscorecard.com/guide.html
Reviewed: 2026-09-19
Author: AGI Scorecard team
Version: 1.5.0

Protocol Ledger is a free, dated reference for five payment, agent-identity and token interfaces. Each record preserves its official specification, review date and interpretation limits. Filter the same snapshot in the browser or retrieve it through the JSON API.

## Method

Serve a versioned editorial snapshot. Filter by purpose or specification status; preserve source, checked date and unsupported conclusions in every record.

## Workflow

1. Select payment, identity or token interface and your maximum acceptable research age.
2. Read the official source behind each short profile.
3. Use /api/v1/profiles or /openapi.json to integrate the same records; reject stale data in your client.

## Common mistake

A current API response can still contain an old research snapshot. Check the original checkedAt and stale fields, not just the request timestamp.

## Worked scenarios

### Explore the five profiles

Inspect the scope, version and official source behind each record.
Fictional inputs: https://protocol.agiscorecard.com/examples/all.json
Run: https://protocol.agiscorecard.com/?scenario=all#workbench
- Profiles: 5
- Checked at: 2026-09-19
- Freshness: Within your age limit

### Payment integration

Find the dated x402 payment profile.
Fictional inputs: https://protocol.agiscorecard.com/examples/payments.json
Run: https://protocol.agiscorecard.com/?scenario=payments#workbench
- Profiles: 1
- Checked at: 2026-09-19
- Freshness: Within your age limit

### Check an old snapshot

Move the review date forward and inspect the stale state.
Fictional inputs: https://protocol.agiscorecard.com/examples/stale.json
Run: https://protocol.agiscorecard.com/?scenario=stale#workbench
- Profiles: 5
- Checked at: 2026-09-19
- Freshness: Review overdue

## Questions

### Does an ERC-8004 registration prove that an agent is trustworthy?

No. A registry can expose identity and feedback signals without proving capabilities, reviewer independence or future performance. Check the official specification and task-specific evidence before relying on an agent.

### Is Protocol Ledger free, and do I need a wallet?

All current functions are free beta. No account, wallet connection, subscription or model API key is needed. Five initial profiles; no market prices, exhaustive schema coverage, real-time protocol monitoring or paid endpoint.

### Can I use my own records and keep them private?

Yes. Enter records, import JSON or paste CSV into record groups. Inputs and comparison snapshots stay in this browser tab. Share-example links contain only a public scenario name. Review downloaded reports before sharing your records.

## Alternatives and official sources

- [The Graph](https://thegraph.com/docs/en/): Blockchain indexing and query infrastructure with Subgraphs and Substreams.
- [Dune](https://docs.dune.com/api-reference/overview/introduction): APIs for querying and retrieving blockchain analytics.

Use The Graph or Dune for chain data and custom analytics. This feed is deliberately about reviewed protocol meanings, not a replacement for indexing or live chain queries.

## Limits

Five initial profiles; no market prices, exhaustive schema coverage, real-time protocol monitoring or paid endpoint.
These are editorial summaries and review checklists, not exhaustive protocol schemas or conformance certificates. Read the linked specification before implementing.

The dataset is a release snapshot. The API reports its original checkedAt and current age; it does not silently refresh the research date. Free access is available; no paid feed is on sale.

## Input and output

Structural schema: https://protocol.agiscorecard.com/input.schema.json
The engine additionally validates ranges, dates, amount formats, uniqueness and cross-field rules.
Input JSON and CSV paste are processed locally. No model, account or wallet is needed.
Reports can be downloaded as JSON or Markdown and printed locally. Public scenario links never include user records.

## Price and license

Current functions are free beta. No paid plan or update SLA is offered.
Tool bundle license: https://protocol.agiscorecard.com/LICENSE.txt
Privacy: https://protocol.agiscorecard.com/privacy.html


## MCP integration

Endpoint: https://protocol.agiscorecard.com/mcp
Transport: Streamable HTTP; no authentication.
Setup and privacy: https://protocol.agiscorecard.com/for-agents.html
Search and fetch provide public citation references. Remote calculator inputs are sent to the server, unlike the local browser worksheet. Application code does not persist MCP arguments or results. Cite the public methodology without claiming it verifies user inputs.