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lean_goal

Read-onlyIdempotent

Get proof goals at a chosen line or column in a Lean file, showing the state before and after a tactic. Use it to verify if the proof is complete or find the goal you need to address.

Instructions

Get proof goals at a position. MOST IMPORTANT tool - use often!

Omit column to see goals_before (line start) and goals_after (line end),
showing how the tactic transforms the state. status='complete' means the
proof is finished at this point; status='no_goal_at_position' means the
position carries no proof state (e.g. outside a proof).

Input Schema

TableJSON Schema

Name	Required	Description	Default
`line`	Yes	Line number (1-indexed)
`column`	No	Column (1-indexed). Omit for before/after
`format`	No	Output format: 'text' (default) or 'structured'	text
`file_path`	Yes	Absolute or project-root-relative path to Lean file
`timeout_s`	No	Max seconds to wait for elaboration. On timeout returns status='still_elaborating' - poll again.

Output Schema

TableJSON Schema

Name	Required	Description
`goals`	No	Goal list at specified column position
`status`	No	Goal status: 'goals' (open goals), 'complete' (no goals left - proof finished here), 'no_goal_at_position' (position carries no proof state), or 'still_elaborating' (timeout_s hit - poll again)
`goals_after`	No	Goals at line end (when column omitted)
`goals_before`	No	Goals at line start (when column omitted)
`line_context`	Yes	Source line where goals were queried

Schema Changelog

Changes observed during successful MCP inspections.

Changed7 schema fields changedv0.28.0Jul 11, 2026

addedInput schema / properties / format

Added value: +{
+  "default": "text",
+  "description": "Output format: 'text' (default) or 'structured'",
+  "enum": [
+    "text",
+    "structured"
+  ],
+  "title": "Format",
+  "type": "string"
+}

addedInput schema / properties / timeout_s

Added value: +{
+  "anyOf": [
+    {
+      "minimum": 1,
+      "type": "number"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Max seconds to wait for elaboration. On timeout returns status='still_elaborating' - poll again.",
+  "title": "Timeout S"
+}

addedOutput schema / $defs

Added value: +{
+  "GoalContextEntry": {
+    "properties": {
+      "name": {
+        "description": "Local hypothesis or variable name",
+        "title": "Name",
+        "type": "string"
+      },
+      "type": {
+        "description": "Lean type",
+        "title": "Type",
+        "type": "string"
+      }
+    },
+    "required": [
+      "name",
+      "type"
+    ],
+    "title": "GoalContextEntry",
+    "type": "object"
+  },
+  "StructuredGoal": {
+    "properties": {
+      "context": {
+        "description": "Local context entries",
+        "items": {
+          "$ref": "#/$defs/GoalContextEntry"
+        },
+        "title": "Context",
+        "type": "array"
+      },
+      "goal": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "null"
+          }
+        ],
+        "default": null,
+        "description": "Target goal",
+        "title": "Goal"
+      },
+      "pretty": {
+        "description": "Original pretty-printed goal",
+        "title": "Pretty",
+        "type": "string"
+      },
+      "status": {
+        "description": "Goal status: open, complete, or unknown",
+        "title": "Status",
+        "type": "string"
+      }
+    },
+    "required": [
+      "status",
+      "pretty"
+    ],
+    "title": "StructuredGoal",
+    "type": "object"
+  }
+}

changedOutput schema / properties / goals / anyOf

Previous value: -[
-  {
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "items": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "$ref": "#/$defs/StructuredGoal"
+        }
+      ]
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

changedOutput schema / properties / goals_after / anyOf

Previous value: -[
-  {
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "items": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "$ref": "#/$defs/StructuredGoal"
+        }
+      ]
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

changedOutput schema / properties / goals_before / anyOf

Previous value: -[
-  {
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  },
-  {
-    "type": "null"
-  }
-]New value: +[
+  {
+    "items": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "$ref": "#/$defs/StructuredGoal"
+        }
+      ]
+    },
+    "type": "array"
+  },
+  {
+    "type": "null"
+  }
+]

addedOutput schema / properties / status

Added value: +{
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Goal status: 'goals' (open goals), 'complete' (no goals left - proof finished here), 'no_goal_at_position' (position carries no proof state), or 'still_elaborating' (timeout_s hit - poll again)",
+  "title": "Status"
+}

Addedv0.10.0May 1, 2026
Removedv0.23.1May 1, 2026
First observedJan 26, 2026

TDQS

A4.6/5.0

Behavior5/5

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

Annotations declare readOnlyHint and idempotentHint, and the description adds crucial behavior: column omission reveals before/after states, timeout handling with 'still_elaborating' status, and possible statuses. No contradictions with annotations.

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?

The description is two sentences plus a status explanation. Front-loaded with 'MOST IMPORTANT tool - use often!' which is slightly verbose but adds emphasis. No extraneous information; each sentence serves a purpose.

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

Completeness5/5

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

Given the complexity of a proof goal tool with 5 parameters and an output schema (not shown), the description adequately covers behavior, status outcomes, and column handling. No missing critical information for using the tool effectively.

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

Parameters4/5

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

Schema covers 100% of parameters with descriptions. The description adds value by explaining the effect of omitting column (goals_before/goals_after) and the meaning of format enum options, which go beyond the schema's parameter descriptions.

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 clearly states 'Get proof goals at a position' with a specific verb and resource. It also labels itself as the 'MOST IMPORTANT tool', distinguishing it from siblings like lean_term_goal, lean_state_search, etc., which query different aspects.

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

Usage Guidelines4/5

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

The description explains when to omit column for before/after views, and defines status values like 'complete' and 'no_goal_at_position'. It does not explicitly list when to use this vs. other tools, but the context of proof goals and the 'most important' emphasis provides implicit guidance.

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