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gitlab mcp

gitlab mcp

by zereight
OverviewSchemaSourceRelated ServersDiscussionsAdmin
TypeScript
Remote

create_merge_request_thread

Start a review thread on a GitLab merge request by submitting a comment body, optionally anchored to a diff position for line-specific feedback.

Instructions

Create a new thread on a merge request. Start a review thread. Use create_merge_request_note for an unthreaded note and create_merge_request_discussion_note to reply.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "project_id": "<project_id>",
      "merge_request_iid": "<merge_request_iid>",
      "body": "<body>"
    },
    "name": "create_merge_request_thread"
  }
}

Input Schema

NameRequiredDescriptionDefault
bodyYesThe content of the thread
jmespathNoOptional JMESPath expression filtering the JSON result before return.
positionNoPosition when creating a diff note
created_atNoDate the thread was created at (ISO 8601 format)
project_idYesProject ID or complete URL-encoded path to project
merge_request_iidYesThe IID of a merge request

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changedv2.1.66
    • addedInput schema / properties / jmespath
      Added value: +{
+  "description": "Optional JMESPath expression filtering the JSON result before return.",
+  "type": "string"
+}
  2. Changed1 schema field changedv2.1.62
    • changedInput schema / required
      Previous value: -[
-  "body",
-  "project_id",
-  "merge_request_iid"
-]New value: +[
+  "project_id",
+  "merge_request_iid",
+  "body"
+]
  3. Addedv2.1.18
  4. Removedv2.1.14
  5. Addedv2.1.11
  6. Removedv2.1.10
  7. Changed8 schema fields changedv2.1.9
    • removedInput schema / additionalProperties
      Removed value: -false
    • removedInput schema / properties / position / additionalProperties
      Removed value: -false
    • changedInput schema / properties / position / properties / height / type
      Previous value: -"number"New value: +[
+  "number",
+  "null"
+]
    • changedInput schema / properties / position / properties / line_range / anyOf
      Previous value: -[
-  {
-    "additionalProperties": false,
-    "description": "Line range for multiline comments on GitLab merge request diffs. VALIDATION RULES: 1) line_code is critical for GitLab API success, 2) start/end must have consistent types, 3) line numbers must form valid range, 4) get line_code from GitLab diff API, never generate manually.",
-    "properties": {
-      "end": {
-        "additionalProperties": false,
-        "description": "End line position for multiline comment range. MUST specify either old_line OR new_line (or both for context), never neither. Range must be valid (end >= start).",
-        "properties": {
-          "line_code": {
-            "description": "CRITICAL: Line identifier in format '{file_path_sha1_hash}_{old_line_number}_{new_line_number}'. USUALLY REQUIRED for GitLab diff comments despite being optional in schema. Example: 'a1b2c3d4e5f6_12_17'. Must be from same file as start.line_code.",
-            "type": [
-              "string",
-              "null"
-            ]
-          },
-          "new_line": {
-            "description": "Line number in modified file (after changes). REQUIRED when type='new', NULL when type='old' (for purely deleted lines), can be present for context lines. MUST be >= start.new_line if both specified.",
-            "type": [
-              "number",
-              "null"
-            ]
-          },
-          "old_line": {
-            "description": "Line number in original file (before changes). REQUIRED when type='old', NULL when type='new' (for purely added lines), can be present for context lines. MUST be >= start.old_line if both specified.",
-            "type": [
-              "number",
-              "null"
-            ]
-          },
-          "type": {
-            "anyOf": [
-              {
-                "enum": [
-                  "new",
-                  "old",
-                  "expanded",
-                  "logic",
-                  "style"
-                ],
-                "type": "string"
-              },
-              {
-                "type": "null"
-              }
-            ],
-            "description": "Line type: 'old' = deleted/original line, 'new' = added/modified line, null = unchanged context. SHOULD MATCH start.type for consistent ranges (don't mix old/new types)."
-          }
-        },
-        "type": "object"
-      },
-      "start": {
-        "additionalProperties": false,
-        "description": "Start line position for multiline comment range. MUST specify either old_line OR new_line (or both for context), never neither.",
-        "properties": {
-          "line_code": {
-            "description": "CRITICAL: Line identifier in format '{file_path_sha1_hash}_{old_line_number}_{new_line_number}'. USUALLY REQUIRED for GitLab diff comments despite being optional in schema. Example: 'a1b2c3d4e5f6_10_15'. Get this from GitLab diff API response, never fabricate.",
-            "type": [
-              "string",
-              "null"
-            ]
-          },
-          "new_line": {
-            "description": "Line number in modified file (after changes). REQUIRED when type='new', NULL when type='old' (for purely deleted lines), can be present for context lines.",
-            "type": [
-              "number",
-              "null"
-            ]
-          },
-          "old_line": {
-            "description": "Line number in original file (before changes). REQUIRED when type='old', NULL when type='new' (for purely added lines), can be present for context lines.",
-            "type": [
-              "number",
-              "null"
-            ]
-          },
-          "type": {
-            "anyOf": [
-              {
-                "enum": [
-                  "new",
-                  "old",
-                  "expanded",
-                  "logic",
-                  "style"
-                ],
-                "type": "string"
-              },
-              {
-                "type": "null"
-              }
-            ],
-            "description": "Line type: 'old' = deleted/original line, 'new' = added/modified line, null = unchanged context. MUST match the line_code format and old_line/new_line values."
-          }
-        },
-        "type": "object"
-      }
-    },
-    "required": [
-      "start",
-      "end"
-    ],
-    "type": "object"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "description": "Line range for multiline comments on GitLab merge request diffs. VALIDATION RULES: 1) line_code is critical for GitLab API success, 2) start/end must have consistent types, 3) line numbers must form valid range, 4) get line_code from GitLab diff API, never generate manually.",
+    "properties": {
+      "end": {
+        "description": "End line position for multiline comment range. MUST specify either old_line OR new_line (or both for context), never neither. Range must be valid (end >= start).",
+        "properties": {
+          "line_code": {
+            "description": "CRITICAL: Line identifier in format '{file_path_sha1_hash}_{old_line_number}_{new_line_number}'. USUALLY REQUIRED for GitLab diff comments despite being optional in schema. Example: 'a1b2c3d4e5f6_12_17'. Must be from same file as start.line_code.",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "new_line": {
+            "description": "Line number in modified file (after changes). REQUIRED when type='new', NULL when type='old' (for purely deleted lines), can be present for context lines. MUST be >= start.new_line if both specified.",
+            "type": [
+              "number",
+              "null"
+            ]
+          },
+          "old_line": {
+            "description": "Line number in original file (before changes). REQUIRED when type='old', NULL when type='new' (for purely added lines), can be present for context lines. MUST be >= start.old_line if both specified.",
+            "type": [
+              "number",
+              "null"
+            ]
+          },
+          "type": {
+            "anyOf": [
+              {
+                "enum": [
+                  "new",
+                  "old",
+                  "expanded",
+                  "logic",
+                  "style"
+                ],
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Line type: 'old' = deleted/original line, 'new' = added/modified line, null = unchanged context. SHOULD MATCH start.type for consistent ranges (don't mix old/new types)."
+          }
+        },
+        "type": "object"
+      },
+      "start": {
+        "description": "Start line position for multiline comment range. MUST specify either old_line OR new_line (or both for context), never neither.",
+        "properties": {
+          "line_code": {
+            "description": "CRITICAL: Line identifier in format '{file_path_sha1_hash}_{old_line_number}_{new_line_number}'. USUALLY REQUIRED for GitLab diff comments despite being optional in schema. Example: 'a1b2c3d4e5f6_10_15'. Get this from GitLab diff API response, never fabricate.",
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "new_line": {
+            "description": "Line number in modified file (after changes). REQUIRED when type='new', NULL when type='old' (for purely deleted lines), can be present for context lines.",
+            "type": [
+              "number",
+              "null"
+            ]
+          },
+          "old_line": {
+            "description": "Line number in original file (before changes). REQUIRED when type='old', NULL when type='new' (for purely added lines), can be present for context lines.",
+            "type": [
+              "number",
+              "null"
+            ]
+          },
+          "type": {
+            "anyOf": [
+              {
+                "enum": [
+                  "new",
+                  "old",
+                  "expanded",
+                  "logic",
+                  "style"
+                ],
+                "type": "string"
+              },
+              {
+                "type": "null"
+              }
+            ],
+            "description": "Line type: 'old' = deleted/original line, 'new' = added/modified line, null = unchanged context. MUST match the line_code format and old_line/new_line values."
+          }
+        },
+        "type": "object"
+      }
+    },
+    "required": [
+      "start",
+      "end"
+    ],
+    "type": "object"
+  },
+  {
+    "type": "null"
+  }
+]
    • changedInput schema / properties / position / properties / width / type
      Previous value: -"number"New value: +[
+  "number",
+  "null"
+]
    • changedInput schema / properties / position / properties / x / type
      Previous value: -"number"New value: +[
+  "number",
+  "null"
+]
    • changedInput schema / properties / position / properties / y / type
      Previous value: -"number"New value: +[
+  "number",
+  "null"
+]
    • changedInput schema / required
      Previous value: -[
-  "body"
-]New value: +[
+  "body",
+  "project_id",
+  "merge_request_iid"
+]
  8. First observedv1.0.0

TDQS

A4.2/5.0
Behavior3/5

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

The annotations only expose `openWorldHint`, so the description carries most of the behavioral burden. It clearly signals a write operation by saying 'Create' and 'Start a review thread', but it does not disclose permission needs, rate limits, reversibility, or how diff-note positioning affects behavior. It is adequate but has clear gaps.

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

Conciseness5/5

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

The description is three short sentences, front-loads the primary action, and immediately routes to alternatives. Every sentence contributes to selecting or using the tool, with no filler.

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

Completeness4/5

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

The input schema is unusually rich, including detailed guidance for diff positions and multiline comments, so the description does not need to repeat those semantics. It is complete enough for tool selection and routing, though it could mention that supplying `position` creates a diff note rather than a general MR thread.

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 the schema already documents all six parameters, including the complex nested `position` object. The description adds no parameter-level meaning beyond the high-level distinction between thread, note, and reply, so baseline 3 is appropriate.

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

Purpose5/5

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

The description states a specific verb and resource: creating a new thread on a merge request, and explicitly frames it as starting a review thread. It also distinguishes this tool from note-creation and reply alternatives, so an agent can identify its role without opening the schema.

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

Usage Guidelines5/5

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

It gives explicit routing guidance: use this tool for a new thread, `create_merge_request_note` for an unthreaded note, and `create_merge_request_discussion_note` to reply. The alternatives and their conditions are named directly.

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

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