ADK-Rust

MCP testing and verification

MCP integrations cross process, transport, schema, and authorization boundaries. Unit tests alone are insufficient; keep at least one deterministic client/server test that completes a real handshake and tool call.

Focused framework gates

cargo test -p adk-tool --features mcp --lib mcp
cargo test -p adk-tool --features mcp --test mcp_roundtrip_property_tests
cargo test -p adk-tool --features mcp,mcp-sampling --test mcp_sampling_property_tests
cargo clippy -p adk-tool --features mcp,http-transport,mcp-sampling -- -D warnings

The sampling gate is compatibility coverage for an upstream-deprecated capability, not a recommendation for new architecture.

Compile integration consumers

cargo check -p adk-acp --all-features
cargo check -p adk-computer-use

These gates catch mismatched public rmcp types across crates that embed or carry MCP configurations.

Standalone examples

cargo check --manifest-path examples/mcp_elicitation/Cargo.toml
cargo check --manifest-path examples/mcp_sampling/Cargo.toml
cargo check --manifest-path examples/mcp_manager/Cargo.toml
cargo run --manifest-path examples/mcp_manager/Cargo.toml

examples/mcp_manager is the deterministic live gate. It starts a real Rust stdio server by executing its own binary in fixture mode. The test does not download a package or contact a remote endpoint.

What the live example proves

  • child-process startup;
  • MCP initialization and capability negotiation;
  • tool discovery;
  • a real tool request and result;
  • runtime add, enable, update, disable, and remove;
  • registry serialization and file persistence; and
  • session shutdown.

What requires deployment-specific testing

  • remote HTTP identity and token policy;
  • full MCP OAuth discovery and user authorization;
  • external API and database health;
  • process sandbox enforcement;
  • tenant isolation;
  • approval UI and audit storage;
  • retry and idempotency behavior for consequential tools; and
  • task recovery after an application restart.

Test server contracts

For every server, keep fixtures for:

  • initialization capability accuracy;
  • tool and resource schemas;
  • invalid and unauthorized inputs;
  • maximum result sizes;
  • cancellation and timeout behavior;
  • idempotent retry of write operations; and
  • redaction of credentials and sensitive fields.