web-debug-mcp

Overview Schema Related Servers Score Discussions

Control paused JavaScript debugger

web_debug_control

Destructive

Control paused JavaScript execution by resuming or stepping through code. Supply a session ID and choose resume, step over, step into, or step out to continue debugging.

Instructions

Resume or step a paused local JavaScript target.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`action`	Yes
`sessionId`	Yes

Output Schema

TableJSON Schema

Name	Required	Description	Default
`ok`	Yes
`data`	No
`error`	No
`warnings`	Yes
`artifacts`	Yes

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

Changed5 schema fields changedv0.7.0Sep 1, 2026

addedOutput schema / properties / data / additionalProperties
```
Added value: +false
```

removedOutput schema / properties / data / allOf

Removed value: -[
-  {
-    "$ref": "#/definitions/__schema0"
-  }
-]

addedOutput schema / properties / data / properties

Added value: +{
+  "breakpoints": {
+    "items": {
+      "additionalProperties": false,
+      "properties": {
+        "column": {
+          "anyOf": [
+            {
+              "maximum": 9007199254740991,
+              "minimum": -9007199254740991,
+              "type": "integer"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
+        "id": {
+          "maxLength": 500,
+          "type": "string"
+        },
+        "line": {
+          "maximum": 9007199254740991,
+          "minimum": -9007199254740991,
+          "type": "integer"
+        },
+        "sourceUrl": {
+          "maxLength": 2560,
+          "type": "string"
+        }
+      },
+      "required": [
+        "id",
+        "sourceUrl",
+        "line",
+        "column"
+      ],
+      "type": "object"
+    },
+    "maxItems": 100,
+    "type": "array"
+  },
+  "callFrames": {
+    "items": {
+      "additionalProperties": false,
+      "properties": {
+        "column": {
+          "maximum": 9007199254740991,
+          "minimum": -9007199254740991,
+          "type": "integer"
+        },
+        "functionName": {
+          "maxLength": 500,
+          "type": "string"
+        },
+        "line": {
+          "maximum": 9007199254740991,
+          "minimum": -9007199254740991,
+          "type": "integer"
+        },
+        "locals": {
+          "additionalProperties": {
+            "$ref": "#/definitions/__schema0"
+          },
+          "propertyNames": {
+            "type": "string"
+          },
+          "type": "object"
+        },
+        "scopeNames": {
+          "items": {
+            "maxLength": 100,
+            "type": "string"
+          },
+          "maxItems": 50,
+          "type": "array"
+        },
+        "url": {
+          "maxLength": 2560,
+          "type": "string"
+        }
+      },
+      "required": [
+        "functionName",
+        "url",
+        "line",
+        "column",
+        "scopeNames",
+        "locals"
+      ],
+      "type": "object"
+    },
+    "maxItems": 50,
+    "type": "array"
+  },
+  "paused": {
+    "type": "boolean"
+  },
+  "reason": {
+    "anyOf": [
+      {
+        "maxLength": 500,
+        "type": "string"
+      },
+      {
+        "type": "null"
+      }
+    ]
+  }
+}

addedOutput schema / properties / data / required

Added value: +[
+  "paused",
+  "reason",
+  "callFrames",
+  "breakpoints"
+]

addedOutput schema / properties / data / type
```
Added value: +"object"
```

First observedv0.5.0-next.0Aug 30, 2026

TDQS

B3.4/5.0

Behavior2/5

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

Annotations already declare destructiveHint=true and idempotent=false, so the mutation risk is known. The description adds no extra behavioral context, such as what happens to the debugger session after resume, whether breakpoints persist, or side effects of stepping.

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 a single sentence where every word adds meaning, front-loading the operation and the required target state. There is no filler or unnecessary detail.

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?

With only two parameters and an output schema present, the tool is relatively simple and the description is adequate. However, it omits parameter roles and any guardrails about the session having to be active or currently paused, so an agent gets the gist but not full operational context.

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

Parameters2/5

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

The input schema has 0% description coverage, and the description does not explain sessionId or the action parameter beyond the enum values already present in the schema. The enum values are readable, but the description does not compensate for the missing schema documentation.

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 uses specific debugger verbs ('Resume', 'step') and identifies the resource ('paused local JavaScript target'), which makes its purpose clear and distinguishable from siblings like web_debug_evaluate or web_breakpoint_set. The title reinforces the same operation without ambiguity.

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

Usage Guidelines3/5

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

The phrase 'paused local JavaScript target' implies the tool should be used only when a debugger session is paused, so the usage context is present. However, it does not explicitly state when not to use the tool or mention alternatives for related tasks such as expression evaluation during a pause.

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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