# InterfaceDelta InterfaceDelta is the independent record of what agent tools can do and when that changed. It observes public machine-readable interfaces (MCP, OpenAPI, A2A, ARD, WebMCP and more) from the outside, keeps every observed version, and records exactly what changed. Facts, not scores: records state observations and change classes, never verdicts about quality or safety. Observation is passive: no tools are called and no credentials are sent. ## About - [InterfaceDelta](https://interfacedelta.com/): The independent record of what agent tools can do and when that changed, operated by InterfaceDelta, Inc. - [About InterfaceDelta](https://interfacedelta.com/about): Who operates the record, what it claims, and what it does not. - [Concepts](https://interfacedelta.com/concepts): Plain definitions of the terms behind the record: MOSHCs (what most people call AI agents), observations, Passports, change classes, effect readings and Record Check. - [company.md](https://interfacedelta.com/company.md): InterfaceDelta described for AI readers: what is live, how we work, what we do not do, and the record’s current numbers with evidence links. ## For agents (machine entry points) - [Public MCP server](https://interfacedelta.com/mcp/public): Read-only MCP server, listed in the Official MCP Registry as com.interfacedelta/atlas. Public tools: get_passport, search_atlas, get_atlas_entry, lookup_domain, list_changes. check_tool reads a full signed Record Check. MCP 0.8.0 adds check_tools for 1–50 goal tools with optional sinceTime (RFC 3339 UTC) and since (exact endpoint#tool to fingerprint map); REST: POST /api/v1/record/check/goal. It returns summary counts and complete signed tools with unsigned changedSinceTime, plus summarySignature over RFC 8785 {summary, signatures: tools.map(t => t.signature)}, using the same EdDSA keys and kid and typ interfacedelta-record-check-goal+jws. Verify the goal body at /api/v1/record/check/verify; unsigned time flags are not authenticated. History is bounded to the latest 20 eligible public observations; false is not proof of no change. Each tool costs one request. Keyless goal admission is atomic: every tool must fit daily and minute quotas or none are consumed; goals over five tools require a key. REST requires a key. See /docs/record-check#check-goal for summary definitions. A few free Record Checks work without a key on the public MCP server: a shared pool of 300 checks per UTC day and a shared burst limit of 5 per minute. Network limits are off by default; if enabled, they allow 10 checks per network per UTC day and 5 per minute per network instead of the shared burst limit. A free agent key gives 250 Record API requests a month. Get a key: POST https://interfacedelta.com/api/v1/agent-keys. Keyless results carry quota {keyless, remainingToday, resetAt} outside the signed result; resetAt is the exhausted minute window or next UTC midnight. - [MCP Events](https://interfacedelta.com/docs/mcp): Experimental events/list and events/poll streams for recorded changes on the MCP servers, when enabled; schemas and polling are documented with the MCP docs. - [Record API (OpenAPI document)](https://interfacedelta.com/api/v1/record/openapi.json): The Record API serves service summaries, latest records and recorded changes; this OpenAPI document describes its endpoints. - [ARD directory](https://interfacedelta.com/.well-known/ard.json): InterfaceDelta declares its own agent interfaces in Agentic Resource Discovery (ARD) format. - [AI catalog](https://interfacedelta.com/.well-known/ai-catalog.json): The same declaration served for AI catalog consumers. - [Capability label keys](https://interfacedelta.com/.well-known/interfacedelta-label-keys.json): The public signing keys (JWKS) that verify capability labels on atlas entries. ## If you publish an MCP server Call lookup_domain {"domain":"example.com"} on https://interfacedelta.com/mcp/public to find retained atlas entries for your domain or URL. Results include observation dates, MCP endpoint URLs and record links. If there are no entries, the response lists possible reasons, not a diagnosis. Publisher instructions: https://interfacedelta.com/atlas/publishers. ## If a person sent you here A person may paste this prompt into you: "Read https://interfacedelta.com/llms.txt and connect to InterfaceDelta's public MCP server (https://interfacedelta.com/mcp/public). Then help me check the agent tools I use: what each one can do, whether it changed recently, and whether it asks for payment. Report the recorded facts, not verdicts." - Connect to the public MCP server at https://interfacedelta.com/mcp/public (no key needed to read). Use search_atlas, then get_atlas_entry. get_atlas_entry returns a short summary by default (view: "summary"); pass view: "full" for the complete record on either MCP server. The summary includes up to 50 tool names, counted AI effect classes, declared hints, five recent changes, label state, observed payment requests (no prices), record links and more.arguments for the full view. It stays below 8,000 JSON characters with toolsOmitted (and toolsOmittedReasons: invalidName, overLimit, size), changesOmitted and registryNamesOmitted counters. effectsAI is null when there is no counted reading and "disputed" when readings disagree. First observed means first retained observation; no recorded payment request does not establish that a service is free. - Read-only lookup_domain {"domain":"example.com"} accepts a domain or http(s) URL and summarizes the host and subdomains, up to 10 services per page, each with targetKey, origin and a more pointer to get_atlas_entry. Read-only list_changes {"since":"2026-11-01T00:00:00Z","domain":"example.com"} returns recorded changes strictly after the UTC time, oldest first, with display classes (not_computed is unclassified) and short field lists. Domain is optional; limit is 1–50, default 20. Copy nextCursor with the same filters. Both tools work on /mcp/public without a key and on /mcp; neither consumes Record API quotas. - For Record Check (check_tool and check_tools) and the Record API, get a free key with one request: POST https://interfacedelta.com/api/v1/agent-keys - Report recorded facts and their dates. Never call a service a safe or unsafe choice; the person decides. ## The atlas - [Agent Web Atlas](https://interfacedelta.com/atlas): The public atlas of observed agent services: detected protocols, MCP endpoint status, revisions and recorded change history. - [This week in agent interfaces](https://interfacedelta.com/atlas/weekly): Seven days of recorded agent interface observations, from the public atlas snapshot. - [How the atlas is built](https://interfacedelta.com/atlas/methodology): How the atlas observes and what it retains; every entry is keyed by an exact target key, /atlas/sha256:<64 hexadecimal characters>, one key per observed service. - Service Markdown: /atlas//service.md renders the stored service record for AI readers. ## Docs - [Docs](https://interfacedelta.com/docs): How InterfaceDelta works and how to use it: inspection, the CLI and GitHub Action, delivery, the REST API and MCP. - [MCP docs](https://interfacedelta.com/docs/mcp): Connecting to the InterfaceDelta MCP servers, their tools and limits, and MCP Events. - [Record API in an enrichment pipeline](https://interfacedelta.com/docs/enrichment): What one Record API domain lookup returns per company domain, with Python and JavaScript waterfall scripts. - [Record API docs](https://interfacedelta.com/docs/rest-api): The Record API section of the REST API page: bearer tokens, endpoints and field semantics. - [Record Check docs](https://interfacedelta.com/docs/record-check): One signed call before an agent acts: Record Check reads stored public observations and never contacts the target service. ## Policies - [Terms of service](https://interfacedelta.com/terms): The terms that govern use of InterfaceDelta. - [Privacy notice](https://interfacedelta.com/privacy): What InterfaceDelta collects, retains and publishes, including the atlas disclosure. - [InterfaceDeltaBot policy](https://interfacedelta.com/bot): The observing bot: identity, passive observation boundaries, traffic limits and opt-out.