Roslyn Workbench MCP

Overview Schema Source Related Servers Discussions Admin

Find Unused Symbols

find-unused-symbols

Read-onlyIdempotent

Detect unused local variables and members in C# code using compiler diagnostics, with filters for scope, internals, generated files, and result limits.

Instructions

Returns candidate unused locals and members from compiler diagnostics.

Input Schema

TableJSON Schema

Name	Required	Description
`scope`	No	The optional search scope.
`workspace`	No	Provide workspaceId, alias, path, or any combination.
`candidatesLimit`	No	Maximum number of results to return.
`includeInternal`	No	Whether internal members should be included.
`excludeGenerated`	No	Whether generated files should be excluded.

Output Schema

TableJSON Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv1.0.4Oct 15, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$defs": {
+    "warningInfo": {
+      "properties": {
+        "code": {
+          "description": "The stable machine-readable warning code.",
+          "type": "string"
+        },
+        "message": {
+          "description": "The human-readable warning message.",
+          "type": "string"
+        }
+      },
+      "required": [
+        "code",
+        "message"
+      ],
+      "type": "object"
+    }
+  },
+  "oneOf": [
+    {
+      "properties": {
+        "data": {
+          "description": "Tool-specific result payload.",
+          "properties": {
+            "candidates": {
+              "description": "The returned unused symbol candidates.",
+              "properties": {
+                "hasMore": {
+                  "description": "Whether additional items were available beyond this page.",
+                  "type": "boolean"
+                },
+                "items": {
+                  "description": "Items returned in this page.",
+                  "items": {
+                    "properties": {
+                      "confidence": {
+                        "description": "The confidence label for the candidate.",
+                        "type": "string"
+                      },
+                      "location": {
+                        "description": "The source location for the candidate.",
+                        "properties": {
+                          "column": {
+                            "description": "The one-based column number.",
+                            "type": "integer"
+                          },
+                          "document": {
+                            "$ref": "#/properties/request/properties/value/properties/candidates/properties/items/items/properties/symbol/properties/location/properties/document",
+                            "description": "The resolved document."
+                          },
+                          "line": {
+                            "description": "The one-based line number.",
+                            "type": "integer"
+                          },
+                          "selector": {
+                            "$ref": "#/properties/request/properties/value/properties/candidates/properties/items/items/properties/symbol/properties/location/properties/selector",
+                            "description": "The canonical selector that can resolve this source location again."
+                          },
+                          "snapshot": {
+                            "$ref": "#/properties/request/properties/value/properties/candidates/properties/items/items/properties/symbol/properties/location/properties/snapshot",
+                            "description": "The exact immutable workspace snapshot associated with this location."
+                          },
+                          "span": {
+                            "$ref": "#/properties/request/properties/value/properties/candidates/properties/items/items/properties/symbol/properties/location/properties/span",
+                            "description": "The resolved text span."
+                          }
+                        },
+                        "required": [
+                          "snapshot"
+                        ],
+                        "type": [
+                          "object",
+                          "null"
+                        ]
+                      },
+                      "reasons": {
+                        "description": "The reasons the symbol was reported.",
+                        "items": {
+                          "type": "string"
+                        },
+                        "type": "array"
+                      },
+                      "symbol": {
+                        "description": "The candidate symbol.",
+                        "properties": {
+                          "displayName": {
+                            "description": "The display name of the symbol.",
+                            "type": "string"
+                          },
+                          "documentationCommentId": {
+                            "description": "The documentation comment identifier, when available.",
+                            "type": [
+                              "string",
+                              "null"
+                            ]
+                          },
+                          "kind": {
+                            "description": "The symbol kind.",
+                            "type": "string"
+                          },
+                          "location": {
+                            "description": "The optional source location of the symbol.",
+                            "properties": {
+                              "column": {
+                                "description": "The one-based column number.",
+                                "type": "integer"
+                              },
+                              "document": {
+                                "description": "The resolved document.",
+                                "properties": {
+                                  "documentId": {
+                                    "description": "The document identifier.",
+                                    "type": "string"
+                                  },
+                                  "path": {
+                                    "description": "The normalized document path.",
+                                    "type": "string"
+                                  },
+                                  "projectId": {
+                                    "description": "The owning project identifier.",
+                                    "type": "string"
+                                  }
+                                },
+                                "required": [
+                                  "documentId",
+                                  "path",
+                                  "projectId"
+                                ],
+                                "type": [
+                                  "object",
+                                  "null"
+                                ]
+                              },
+                              "line": {
+                                "description": "The one-based line number.",
+                                "type": "integer"
+                              },
+                              "selector": {
+                                "description": "The canonical selector that can resolve this source location again.",
+                                "properties": {
+                                  "span": {
+                                    "properties": {
+                                      "document": {
+                                        "description": "Provide exactly one of path or documentId.",
+                                        "properties": {
+                                          "documentId": {
+                                            "description": "Workspace-local document ID.",
+                                            "type": [
+                                              "string",
+                                              "null"
+                                            ]
+                                          },
+                                          "path": {
+                                            "description": "Workspace-relative path.",
+                                            "type": [
+                                              "string",
+                                              "null"
+                                            ]
+                                          },
+                                          "project": {
+                                            "description": "Disambiguates documents with matching paths or IDs.",
+                                            "properties": {
+                                              "name": {
+                                                "type": [
+                                                  "string",
+                                                  "null"
+                                                ]
+                                              },
+                                              "path": {
+                                                "description": "Workspace-relative path.",
+                                                "type": [
+                                                  "string",
+                                                  "null"
+                                                ]
+                                              },
+                                              "projectId": {
+                                                "type": [
+                                                  "string",
+                                                  "null"
+                                                ]
+                                              },
+                                              "targetFramework": {
+                                                "type": [
+                                                  "string",
+                                                  "null"
+                                                ]
+                                              }
+                                            },
+                                            "type": [
+                                              "object",
+                                              "null"
+                                            ]
+                                          }
+                                        },
+                                        "type": "object"
+                                      },
+                                      "range": {
+                                        "description": "Zero-based UTF-16 range.",
+                                        "properties": {
+                                          "length": {
+                                            "description": "UTF-16 code-unit length.",
+                                            "maximum": 2147483647,
+                                            "minimum": 0,
+                                            "type": "integer"
+                                          },
+                                          "start": {
+                                            "description": "Zero-based UTF-16 offset.",
+                                            "maximum": 2147483647,
+                                            "minimum": 0,
+                                            "type": "integer"
+                                          }
+                                        },
+                                        "type": "object"
+                                      }
+                                    },
+                                    "required": [
+                                      "document",
+                                      "range"
+                                    ],
+                                    "type": "object"
+                                  }
+                                },
+                                "required": [
+                                  "span"
+                                ],
+                                "type": [
+                                  "object",
+                                  "null"
+                                ]
+                              },
+                              "snapshot": {
+                                "description": "The exact immutable workspace snapshot associated with this location.",
+                                "properties": {
+                                  "snapshotId": {
+                                    "format": "uuid",
+                                    "type": "string"
+                                  },
+                                  "transactionRevision": {
+                                    "type": [
+                                      "integer",
+                                      "null"
+                                    ]
+                                  },
+                                  "workspaceEpoch": {
+                                    "type": "integer"
+                                  },
+                                  "workspaceId": {
+                                    "format": "uuid",
+                                    "type": "string"
+                                  }
+                                },
+                                "required": [
+                                  "workspaceId",
+                                  "workspaceEpoch",
+                                  "snapshotId",
+                                  "transactionRevision"
+                                ],
+                                "type": "object"
+                              },
+                              "span": {
+                                "description": "The resolved text span.",
+                                "properties": {
+                                  "length": {
+                                    "description": "UTF-16 code-unit length.",
+                                    "maximum": 2147483647,
+                                    "minimum": 0,
+                                    "type": "integer"
+                                  },
+                                  "start": {
+                                    "description": "Zero-based UTF-16 offset.",
+                                    "maximum": 2147483647,
+                                    "minimum": 0,
+                                    "type": "integer"
+                                  }
+                                },
+                                "type": [
+                                  "object",
+                                  "null"
+                                ]
+                              }
+                            },
+                            "required": [
+                              "snapshot"
+                            ],
+                            "type": [
+                              "object",
+                              "null"
+                            ]
+                          }
+                        },
+                        "required": [
+                          "displayName",
+                          "kind"
+                        ],
+                        "type": [
+                          "object",
+                          "null"
+                        ]
+                      }
+                    },
+                    "required": [
+                      "confidence"
+                    ],
+                    "type": "object"
+                  },
+                  "type": [
+                    "array",
+                    "null"
+                  ]
+                },
+                "totalCount": {
+                  "description": "Complete result count, when available without additional expensive work.",
+                  "type": [
+                    "integer",
+                    "null"
+                  ]
+                }
+              },
+              "type": "object"
+            }
+          },
+          "type": [
+            "object",
+            "null"
+          ]
+        },
+        "ok": {
+          "const": true,
+          "description": "Whether the tool invocation succeeded."
+        },
+        "snapshot": {
+          "description": "Exact immutable workspace snapshot associated with the result, when available.",
+          "properties": {
+            "snapshotId": {
+              "format": "uuid",
+              "type": "string"
+            },
+            "transactionRevision": {
+              "type": [
+                "integer",
+                "null"
+              ]
+            },
+            "workspaceEpoch": {
+              "type": "integer"
+            },
+            "workspaceId": {
+              "format": "uuid",
+              "type": "string"
+            }
+          },
+          "required": [
+            "workspaceId",
+            "workspaceEpoch",
+            "snapshotId",
+            "transactionRevision"
+          ],
+          "type": "object"
+        },
+        "warnings": {
+          "description": "Non-fatal warnings the agent should consider.",
+          "items": {
+            "$ref": "#/$defs/warningInfo"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "ok",
+        "data",
+        "snapshot"
+      ],
+      "type": "object"
+    },
+    {
+      "properties": {
+        "continuation": {
+          "description": "Action the agent should take before retrying or continuing.",
+          "oneOf": [
+            {
+              "additionalProperties": false,
+              "properties": {
+                "instruction": {
+                  "description": "Agent-facing instruction explaining how to continue.",
+                  "minLength": 1,
+                  "type": "string"
+                },
+                "kind": {
+                  "const": "CallTool",
+                  "description": "Action required before the original request can continue."
+                },
+                "tool": {
+                  "description": "Tool to call before continuing the original request.",
+                  "minLength": 1,
+                  "type": "string"
+                }
+              },
+              "required": [
+                "kind",
+                "tool",
+                "instruction"
+              ],
+              "type": "object"
+            },
+            {
+              "additionalProperties": false,
+              "properties": {
+                "instruction": {
+                  "description": "Agent-facing instruction explaining how to continue.",
+                  "minLength": 1,
+                  "type": "string"
+                },
+                "kind": {
+                  "const": "ChooseTool",
+                  "description": "Action required before the original request can continue."
+                },
+                "tools": {
+                  "description": "Allowed tool choices from which the agent must select one.",
+                  "items": {
+                    "description": "Name of a tool the agent may choose.",
+                    "minLength": 1,
+                    "type": "string"
+                  },
+                  "minItems": 1,
+                  "type": "array",
+                  "uniqueItems": true
+                }
+              },
+              "required": [
+                "kind",
+                "tools",
+                "instruction"
+              ],
+              "type": "object"
+            },
+            {
+              "additionalProperties": false,
+              "properties": {
+                "instruction": {
+                  "description": "Agent-facing instruction explaining how to continue.",
+                  "minLength": 1,
+                  "type": "string"
+                },
+                "kind": {
+                  "const": "RetryRequest",
+                  "description": "Action required before the original request can continue."
+                }
+              },
+              "required": [
+                "kind",
+                "instruction"
+              ],
+              "type": "object"
+            },
+            {
+              "additionalProperties": false,
+              "properties": {
+                "instruction": {
+                  "description": "Agent-facing instruction explaining how to continue.",
+                  "minLength": 1,
+                  "type": "string"
+                },
+                "kind": {
+                  "const": "ReviseRequest",
+                  "description": "Action required before the original request can continue."
+                }
+              },
+              "required": [
+                "kind",
+                "instruction"
+              ],
+              "type": "object"
+            },
+            {
+              "additionalProperties": false,
+              "properties": {
+                "instruction": {
+                  "description": "Agent-facing instruction explaining how to continue.",
+                  "minLength": 1,
+                  "type": "string"
+                },
+                "kind": {
+                  "const": "ResolveExternally",
+                  "description": "Action required before the original request can continue."
+                }
+              },
+              "required": [
+                "kind",
+                "instruction"
+              ],
+              "type": "object"
+            }
+          ]
+        },
+        "diagnostics": {
+          "description": "Diagnostics that explain the failed invocation.",
+          "items": {
+            "properties": {
+              "id": {
+                "description": "The diagnostic identifier.",
+                "type": "string"
+              },
+              "location": {
+                "description": "The optional source location of the diagnostic.",
+                "properties": {
+                  "column": {
+                    "description": "The one-based column number.",
+                    "type": "integer"
+                  },
+                  "document": {
+                    "description": "The resolved document.",
+                    "properties": {
+                      "documentId": {
+                        "description": "The document identifier.",
+                        "type": "string"
+                      },
+                      "path": {
+                        "description": "The normalized document path.",
+                        "type": "string"
+                      },
+                      "projectId": {
+                        "description": "The owning project identifier.",
+                        "type": "string"
+                      }
+                    },
+                    "required": [
+                      "documentId",
+                      "path",
+                      "projectId"
+                    ],
+                    "type": [
+                      "object",
+                      "null"
+                    ]
+                  },
+                  "line": {
+                    "description": "The one-based line number.",
+                    "type": "integer"
+                  },
+                  "selector": {
+                    "description": "The canonical selector that can resolve this source location again.",
+                    "properties": {
+                      "span": {
+                        "properties": {
+                          "document": {
+                            "description": "Provide exactly one of path or documentId.",
+                            "properties": {
+                              "documentId": {
+                                "description": "Workspace-local document ID.",
+                                "type": [
+                                  "string",
+                                  "null"
+                                ]
+                              },
+                              "path": {
+                                "description": "Workspace-relative path.",
+                                "type": [
+                                  "string",
+                                  "null"
+                                ]
+                              },
+                              "project": {
+                                "description": "Disambiguates documents with matching paths or IDs.",
+                                "properties": {
+                                  "name": {
+                                    "type": [
+                                      "string",
+                                      "null"
+                                    ]
+                                  },
+                                  "path": {
+                                    "description": "Workspace-relative path.",
+                                    "type": [
+                                      "string",
+                                      "null"
+                                    ]
+                                  },
+                                  "projectId": {
+                                    "type": [
+                                      "string",
+                                      "null"
+                                    ]
+                                  },
+                                  "targetFramework": {
+                                    "type": [
+                                      "string",
+                                      "null"
+                                    ]
+                                  }
+                                },
+                                "type": [
+                                  "object",
+                                  "null"
+                                ]
+                              }
+                            },
+                            "type": "object"
+                          },
+                          "range": {
+                            "description": "Zero-based UTF-16 range.",
+                            "properties": {
+                              "length": {
+                                "description": "UTF-16 code-unit length.",
+                                "maximum": 2147483647,
+                                "minimum": 0,
+                                "type": "integer"
+                              },
+                              "start": {
+                                "description": "Zero-based UTF-16 offset.",
+                                "maximum": 2147483647,
+                                "minimum": 0,
+                                "type": "integer"
+                              }
+                            },
+                            "type": "object"
+                          }
+                        },
+                        "required": [
+                          "document",
+                          "range"
+                        ],
+                        "type": "object"
+                      }
+                    },
+                    "required": [
+                      "span"
+                    ],
+                    "type": [
+                      "object",
+                      "null"
+                    ]
+                  },
+                  "snapshot": {
+                    "description": "The exact immutable workspace snapshot associated with this location.",
+                    "properties": {
+                      "snapshotId": {
+                        "format": "uuid",
+                        "type": "string"
+                      },
+                      "transactionRevision": {
+                        "type": [
+                          "integer",
+                          "null"
+                        ]
+                      },
+                      "workspaceEpoch": {
+                        "type": "integer"
+                      },
+                      "workspaceId": {
+                        "format": "uuid",
+                        "type": "string"
+                      }
+                    },
+                    "required": [
+                      "workspaceId",
+                      "workspaceEpoch",
+                      "snapshotId",
+                      "transactionRevision"
+                    ],
+                    "type": "object"
+                  },
+                  "span": {
+                    "description": "The resolved text span.",
+                    "properties": {
+                      "length": {
+                        "description": "UTF-16 code-unit length.",
+                        "maximum": 2147483647,
+                        "minimum": 0,
+                        "type": "integer"
+                      },
+                      "start": {
+                        "description": "Zero-based UTF-16 offset.",
+                        "maximum": 2147483647,
+                        "minimum": 0,
+                        "type": "integer"
+                      }
+                    },
+                    "type": [
+                      "object",
+                      "null"
+                    ]
+                  }
+                },
+                "required": [
+                  "snapshot"
+                ],
+                "type": [
+                  "object",
+                  "null"
+                ]
+              },
+              "message": {
+                "description": "The diagnostic message.",
+                "type": "string"
+              },
+              "severity": {
+                "description": "The diagnostic severity.",
+                "enum": [
+                  "Hidden",
+                  "Info",
+                  "Warning",
+                  "Error"
+                ],
+                "type": "string"
+              }
+            },
+            "required": [
+              "id",
+              "message"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "error": {
+          "description": "Structured error details when the invocation failed.",
+          "properties": {
+            "code": {
+              "description": "Stable machine-readable error code.",
+              "type": "string"
+            },
+            "correlationId": {
+              "description": "Correlation identifier for matching the failure to server-side diagnostics, when available.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "message": {
+              "description": "Human-readable explanation of the failure.",
+              "type": "string"
+            }
+          },
+          "required": [
+            "code",
+            "message"
+          ],
+          "type": "object"
+        },
+        "ok": {
+          "const": false,
+          "description": "Whether the tool invocation succeeded."
+        },
+        "warnings": {
+          "description": "Non-fatal warnings the agent should consider.",
+          "items": {
+            "$ref": "#/$defs/warningInfo"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "ok",
+        "error"
+      ],
+      "type": "object"
+    },
+    {
+      "properties": {
+        "diagnostics": {
+          "description": "Diagnostics that explain the failed invocation.",
+          "properties": {
+            "detailsAvailable": {
+              "const": true
+            },
+            "detailsTool": {
+              "const": "get-error-details"
+            }
+          },
+          "required": [
+            "detailsAvailable",
+            "detailsTool"
+          ],
+          "type": "object"
+        },
+        "error": {
+          "description": "Structured error details when the invocation failed.",
+          "properties": {
+            "code": {
+              "const": "UnhandledException"
+            },
+            "correlationId": {
+              "format": "uuid",
+              "type": "string"
+            },
+            "message": {
+              "const": "Tool execution failed."
+            }
+          },
+          "required": [
+            "code",
+            "message",
+            "correlationId"
+          ],
+          "type": "object"
+        },
+        "ok": {
+          "const": false,
+          "description": "Whether the tool invocation succeeded."
+        },
+        "reporting": {
+          "description": "Error-reporting workflow available for an unhandled failure.",
+          "properties": {
+            "canPrepare": {
+              "type": "boolean"
+            },
+            "prepareTool": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "state": {
+              "enum": [
+                "Available",
+                "AlwaysApproved",
+                "DisabledByConfiguration",
+                "ApprovalUnavailable"
+              ],
+              "type": "string"
+            }
+          },
+          "required": [
+            "state"
+          ],
+          "type": "object"
+        }
+      },
+      "required": [
+        "ok",
+        "error",
+        "diagnostics"
+      ],
+      "type": "object"
+    }
+  ],
+  "type": "object"
+}

First observedv1.0.2Oct 15, 2026

TDQS

B3.2/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral caveat the annotations do not: results are 'candidate' symbols derived from compiler diagnostics, i.e. heuristics rather than an authoritative call graph. It says nothing about result volume or how candidatesLimit affects output.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

One short, front-loaded sentence with zero filler. It is efficient, though the terseness borders on under-specification given the tool's five-parameter surface.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return-value explanation is not required, and annotations cover the safety profile. What remains missing is routing context and any hint about scope defaults or result volume, which matters for a tool with five optional parameters.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so every parameter (scope kinds, workspace, candidatesLimit, includeInternal, excludeGenerated) is already documented in the schema. The description adds no additional parameter meaning, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a concrete verb (Returns) and a specific resource (unused locals and members), plus the data source (compiler diagnostics). That is enough to distinguish it from diagnostic-oriented siblings like get-diagnostics and reference-oriented ones like find-references, though it never names an alternative explicitly.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no when-to-use statement, no prerequisites, and no mention of when another tool (e.g. find-references or get-diagnostics) is the better choice. The agent must infer the use case purely from the tool name.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server