Foundry as Master, Bedrock as Remote: The Smoke Test Finally Passed

A developer successfully demonstrated a cross-cloud AI agent integration where Microsoft Foundry acts as the master coordinator and Amazon Bedrock AgentCore as a remote specialist, using the Agent2Agent (A2A) protocol. The smoke test on July 30, 2026, verified that Foundry can execute a local MCP baseline, call an AgentCore A2A agent, and apply deterministic verification, with the verified result showing exact agreement between the two paths. The repository, xbill9/foundry-bedrock-a2a-currency, passes 66 deterministic tests and includes a custom JWT authorizer for AgentCore to handle authentication across clouds.

I wanted one specific piece of coverage: Microsoft Foundry master ├── MCP ── live exchange-rate baseline └── A2A ── Amazon Bedrock AgentCore remote specialist On July 30, 2026, that direction worked end to end. This matters because I had already tested the reverse topology—AgentCore as coordinator and Foundry as remote. A cross-cloud claim based on only one direction is weak. This run proves Foundry can own the request, execute its local MCP baseline, call an AgentCore A2A agent, and apply deterministic verification. The code and sanitized evidence are in xbill9/foundry-bedrock-a2a-currency https://github.com/xbill9/foundry-bedrock-a2a-currency . The input was 100 USD → EUR . I invoked the Foundry-hosted coordinator through its Responses endpoint in all three benchmark modes: | Mode | Path | Observed result | Adapter time | |---|---|---|---| mcp only | Foundry → local MCP | 87.13800 EUR | 359 ms | a2a only | Foundry → A2A → AgentCore | 87.138 EUR | 25,105 ms | verified | both paths concurrently | exact agreement | 28,163 ms | The verified result reported: { "relative difference": "0", "agreed": true, "failures": {} } That is one smoke case, not a latency distribution and not a completed benchmark matrix. The useful conclusion is narrower: the Foundry-master cloud boundary works, including authentication, discovery, invocation, and deterministic comparison. The repository also passes 66 deterministic tests; one optional integration test is skipped without its external dependency. Currency conversion makes interoperability easy to falsify. Every quote carries the amount, rate, converted amount, observation time, source, and adapter latency. Money and rates use Python Decimal . The coordinator—not an LLM—checks agreement: difference = abs primary.converted amount - verifier.converted amount relative difference = difference / abs primary.converted amount agreed = relative difference <= Decimal "0.005" The model handles intent and chooses one tool call. Framework-independent code owns arithmetic, concurrency, timeout policy, and failure reporting. The stable application depends on two interfaces: ExchangeRateTool ; RemoteCurrencyAgent .Microsoft Agent Framework and Foundry hosting sit outside those interfaces. Strands and AgentCore sit outside them on the other side. Flipping the clouds did not require rewriting the domain service. That is more valuable than merely getting two SDKs into one process. Each cloud can be deployed independently, and the benchmark can still compare MCP-only, A2A-only, and verified execution. AgentCore's default runtime authorization is IAM/SigV4. That is appropriate for AWS callers, but a Foundry-hosted container does not automatically have AWS credentials. For this test I configured AgentCore with a custom JWT authorizer and used a Cognito machine-to-machine client: Foundry container ├── client credentials ── Cognito token endpoint └── Bearer JWT ────────── AgentCore A2A runtime The coordinator's A2A adapter now supports OAuth client credentials, caches the token until shortly before expiry, and retains static bearer support for other peer profiles. The AgentCore authorizer validates the issuer, client, and required currencybench/invoke scope. No token participates in the domain layer. The successful diagram hides most of the work. These were observed failures, not hypothetical risks. The coordinator client uses A2A 1.x. AgentCore's A2A extra currently requires the 0.3 line in the deployed server bundle. Installing both into the same bundle produced an unsatisfiable dependency graph. The fix was architectural: pin the AgentCore application bundle to its compatible A2A SDK while keeping the Foundry-side client separate. The network protocol interoperated even though the Python packages did not share a version. A direct AWS CLI invocation worked, but the Foundry container could not sign an AWS request. Switching the runtime to custom JWT authorization and adding the OAuth adapter made the remote callable without embedding AWS credentials. The first hosted a2a only call failed cleanly: { "failures": { "a2a": "timeout: adapter timed out" }, "elapsed ms": 10010 } A direct remote call had already taken about 25 seconds. The adapter was working; the benchmark policy was too aggressive for a cold cross-cloud path. The hosted timeout is now 60 seconds. The next A2A-only invocation completed in 25.1 seconds. The hosted-agent remote build repeatedly ended with ImageError: Container . I switched to a prebuilt, digest-pinned image in Azure image not found Container Registry. The next failure was more precise: registry authentication. Three identities were visible—the Foundry account, the project, and the per-agent runtime identity. Image pull uses the project managed identity . Granting the other two AcrPull did not help. The deployment became active after: A soft-deleted Foundry account blocked recreation until it was purged. Project role assignments also took time to propagate. Those are deployment-plane facts, distinct from whether A2A works at runtime. In verified mode, Foundry started both adapters. Its MCP leg returned rate 0.87138 ; the AgentCore specialist returned rate 0.87138 . Deterministic code computed a relative difference of zero and marked the quotes as agreed. The MCP result also carried a stale-observation warning. The coordinator preserved it rather than letting the model smooth it away. The hosted response took about 45 seconds end to end while the measured adapter work took 28.2 seconds. That gap includes model and hosted-response overhead. With one observation, it would be irresponsible to call either number a benchmark. Observed: Not yet established: That distinction is the point of the project. The result is coverage, not a victory lap: Microsoft Foundry works as the main cloud, and Amazon Bedrock AgentCore works as its authenticated remote A2A specialist.