diff --git a/gitnexus/src/mcp/tools.ts b/gitnexus/src/mcp/tools.ts
index 5db37438e..9591213c6 100644
--- a/gitnexus/src/mcp/tools.ts
+++ b/gitnexus/src/mcp/tools.ts
@@ -476,7 +476,7 @@ SERVICE: optional monorepo path prefix (case-sensitive path segments). When "rep
           // statement anchor" and is tolerated on the callgraph path.
           minimum: 0,
           description:
-            "1-based source line — PDG statement anchor (mode:'pdg'). Seeds affectedStatements on the statement at this line; inter-procedural symbols are still returned in interproceduralByDepth/pdgInterprocedural and the compatibility byDepth bucket. 0 (or omitted) means no statement anchor; mode:'pdg' requires a positive line.",
+            "1-based source line — PDG statement anchor (mode:'pdg'). Seeds affectedStatements on the statement at this line; inter-procedural symbols are still returned in interproceduralByDepth/pdgInterprocedural and the compatibility byDepth bucket. Omit line for whole-symbol pdg (whole-symbol reach + diagnostics); a positive line anchors a statement slice. Literal 0 is tolerated only as an omitted-line compatibility sentinel on the callgraph path and is rejected for mode:'pdg'.",
         },
         file_path: {
           type: 'string',
diff --git a/gitnexus/test/unit/tools.test.ts b/gitnexus/test/unit/tools.test.ts
index 0b90061a8..076c4dae2 100644
--- a/gitnexus/test/unit/tools.test.ts
+++ b/gitnexus/test/unit/tools.test.ts
@@ -146,10 +146,15 @@ describe('GITNEXUS_TOOLS', () => {
     // Statement-anchored slice is optional — never required.
     expect(impactTool.inputSchema.required).not.toContain('line');
     // The description names the mode:'pdg' statement-anchor semantics and the
-    // 0/omitted = no-anchor compatibility convention.
+    // literal-0 compatibility convention — without contradicting the top-level
+    // "omit line for whole-symbol pdg" contract (#2283).
     expect(line.description).toMatch(/statement anchor/i);
     expect(line.description).toMatch(/pdg/i);
-    expect(line.description).toMatch(/0 \(or omitted\) means no statement anchor/i);
+    expect(line.description).toMatch(/literal 0 is tolerated only .* on the callgraph path/i);
+    expect(line.description).toMatch(/omit line for whole-symbol pdg/i);
+    // Must NOT claim pdg "requires a positive line" — that contradicts the valid
+    // no-line whole-symbol pdg call documented in the top-level description.
+    expect(line.description).not.toMatch(/requires a positive line/i);
     // The top-level description mentions the statement-anchored slice and result shape.
     expect(impactTool.description).toMatch(/statement-anchored|STATEMENT-ANCHORED/);
     expect(impactTool.description).toContain('affectedStatements');