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Merge pull request #333 from koic/tool_validation_error

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Return tool argument validation failures as tool execution errors
This commit is contained in:
Koichi ITO 2026-05-02 01:09:26 +09:00 • committed by GitHub
commit 38d952adce
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GPG key ID: B5690EEEBB952194
2 changed files with 88 additions and 27 deletions
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4
lib/mcp/server.rb
View file

@ -533,7 +533,7 @@ module MCP
add_instrumentation_data(error: :missing_required_arguments)
missing = tool.input_schema.missing_required_arguments(arguments).join(", ")
raise RequestHandlerError.new("Missing required arguments: #{missing}", request, error_type: :invalid_params)
return error_tool_response("Missing required arguments: #{missing}")
end
if configuration.validate_tool_call_arguments && tool.input_schema
@ -542,7 +542,7 @@ module MCP
rescue Tool::InputSchema::ValidationError => e
add_instrumentation_data(error: :invalid_schema)
raise RequestHandlerError.new(e.message, request, error_type: :invalid_params)
return error_tool_response(e.message)
end
end

111
test/mcp/server_test.rb
View file

@ -312,7 +312,7 @@ module MCP
assert_instrumentation_data({ method: "tools/call", tool_name: tool_name, tool_arguments: tool_args })
end
test "#handle tools/call returns protocol error in JSON-RPC format if required tool arguments are missing" do
test "#handle tools/call returns tool execution error if required tool arguments are missing" do
tool_with_required_argument = Tool.define(
name: "test_tool",
title: "Test tool",
@ -336,10 +336,10 @@ module MCP
response = server.handle(request)
assert_nil response[:result]
assert_equal(-32602, response[:error][:code])
assert_equal "Invalid params", response[:error][:message]
assert_includes response[:error][:data], "Missing required arguments: message"
assert_nil response[:error]
assert(response[:result][:isError])
assert_equal "text", response[:result][:content][0][:type]
assert_includes response[:result][:content][0][:text], "Missing required arguments: message"
end
test "#handle_json tools/call executes tool and returns result" do
@ -1562,11 +1562,10 @@ module MCP
refute response[:result].key?(:instructions)
end
test "tools/call returns protocol error in JSON-RPC format for missing arguments" do
server = Server.new(
tools: [TestTool],
configuration: Configuration.new(validate_tool_call_arguments: true),
)
test "tools/call returns tool execution error for missing arguments" do
configuration = Configuration.new(validate_tool_call_arguments: true)
configuration.instrumentation_callback = instrumentation_helper.callback
server = Server.new(tools: [TestTool], configuration: configuration)
response = server.handle(
{
@ -1581,17 +1580,22 @@ module MCP
assert_equal "2.0", response[:jsonrpc]
assert_equal 1, response[:id]
assert_nil response[:result]
assert_equal(-32602, response[:error][:code])
assert_equal "Invalid params", response[:error][:message]
assert_includes response[:error][:data], "Missing required arguments"
assert_nil response[:error]
assert(response[:result][:isError])
assert_equal "text", response[:result][:content][0][:type]
assert_includes response[:result][:content][0][:text], "Missing required arguments"
assert_instrumentation_data({
method: "tools/call",
tool_name: "test_tool",
tool_arguments: {},
error: :missing_required_arguments,
})
end
test "tools/call returns protocol error in JSON-RPC format for invalid arguments when validate_tool_call_arguments is true" do
server = Server.new(
tools: [TestTool],
configuration: Configuration.new(validate_tool_call_arguments: true),
)
test "tools/call returns tool execution error for invalid arguments when validate_tool_call_arguments is true" do
configuration = Configuration.new(validate_tool_call_arguments: true)
configuration.instrumentation_callback = instrumentation_helper.callback
server = Server.new(tools: [TestTool], configuration: configuration)
response = server.handle(
{
@ -1607,10 +1611,44 @@ module MCP
assert_equal "2.0", response[:jsonrpc]
assert_equal 1, response[:id]
assert_nil response[:result]
assert_equal(-32602, response[:error][:code])
assert_equal "Invalid params", response[:error][:message]
assert_includes response[:error][:data], "Invalid arguments"
assert_nil response[:error]
assert(response[:result][:isError])
assert_equal "text", response[:result][:content][0][:type]
assert_includes response[:result][:content][0][:text], "Invalid arguments"
assert_instrumentation_data({
method: "tools/call",
tool_name: "test_tool",
tool_arguments: { message: 123 },
error: :invalid_schema,
})
end
test "tools/call returns tool execution error for nested schema validation failure" do
server = Server.new(
tools: [ComplexTypesTool],
configuration: Configuration.new(validate_tool_call_arguments: true),
)
response = server.handle(
{
jsonrpc: "2.0",
id: 1,
method: "tools/call",
params: {
name: "complex_types_tool",
arguments: {
numbers: [1, 2, 3],
strings: ["a", "b", "c"],
objects: [{ name: 123 }],
},
},
},
)
assert_nil response[:error]
assert(response[:result][:isError])
assert_equal "text", response[:result][:content][0][:type]
assert_includes response[:result][:content][0][:text], "Invalid arguments"
end
test "tools/call skips argument validation when validate_tool_call_arguments is false" do
@ -1695,7 +1733,7 @@ module MCP
assert_equal "OK", response[:result][:content][0][:content]
end
test "tools/call returns protocol error in JSON-RPC format when additionalProperties set to false" do
test "tools/call returns tool execution error when additionalProperties set to false" do
server = Server.new(
tools: [TestToolWithAdditionalPropertiesSetToFalse],
configuration: Configuration.new(validate_tool_call_arguments: true),
@ -1718,10 +1756,33 @@ module MCP
assert_equal "2.0", response[:jsonrpc]
assert_equal 1, response[:id]
assert_nil response[:error]
assert(response[:result][:isError])
assert_equal "text", response[:result][:content][0][:type]
assert_includes response[:result][:content][0][:text], "Invalid arguments"
end
test "tools/call returns JSON-RPC -32602 protocol error when tool is not found" do
server = Server.new(
tools: [TestTool],
)
response = server.handle(
{
jsonrpc: "2.0",
id: 1,
method: "tools/call",
params: {
name: "unknown_tool",
arguments: {},
},
},
)
assert_nil response[:result]
assert_equal(-32602, response[:error][:code])
assert_equal "Invalid params", response[:error][:message]
assert_includes response[:error][:data], "Invalid arguments"
assert_includes response[:error][:data], "Tool not found: unknown_tool"
end
test "#handle completion/complete returns default completion result" do