mcp-vdd

Generate Plan

vdd_plan

Destructive

Generate the technical blueprint for a feature, producing plan.md, data-model.md, and contracts. Run after vdd_specify or vdd_clarify, before vdd_tasks.

Instructions

VDD Phase 5: Generate the technical blueprint under vdd/specs// — plan.md (component breakdown, AC coverage map, technology choices, verification toolchain), data-model.md (entities, indexes, migrations), and contracts/ (request/response/error schemas). Overwrites these files. Requires an existing spec for the feature; run after vdd_specify or vdd_clarify and before vdd_tasks — if no spec exists yet, run vdd_specify first. Parameter relationships: feature must match the value passed to vdd_specify and vdd_tasks.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`feature`	Yes	Feature name: the vdd/specs/<feature>/ directory, kebab-case (e.g., "user-auth"); must reference a directory created earlier by vdd_specify
`projectRoot`	No	Project root: directory that constitution.md and the vdd/ folder are written to and resolved against. Relative paths resolve from the current working directory; keep the same value across every phase (default ".")	.

Output Schema

TableJSON Schema

Name	Required	Description
`_sdt`	Yes	Strategy-and-Tactic instructions for the next step
`error`	No	Error message when the phase fails
`_phase`	Yes	VDD phase that produced this result
`output`	No	Additional structured phase output
`success`	Yes	Whether the phase completed successfully
`artifact`	No	Primary artifact produced or returned
`gateResult`	No	Quality-gate result, when the phase runs a gate

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv1.9.0Oct 2, 2026

changedInput schema / properties / feature / description

Previous value: -"Feature name (spec directory name)"New value: +"Feature name: the vdd/specs/<feature>/ directory, kebab-case (e.g., \"user-auth\"); must reference a directory created earlier by vdd_specify"

changedInput schema / properties / projectRoot / description

Previous value: -"Project root: directory that constitution.md and the vdd/ folder are written to and resolved against (default \".\")"New value: +"Project root: directory that constitution.md and the vdd/ folder are written to and resolved against. Relative paths resolve from the current working directory; keep the same value across every phase (default \".\")"

Changed1 schema field changedv0.1.3Sep 24, 2026

changedInput schema / properties / projectRoot / description

Previous value: -"Path to project root directory"New value: +"Project root: directory that constitution.md and the vdd/ folder are written to and resolved against (default \".\")"

Changed1 schema field changedv0.1.2Sep 24, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "additionalProperties": false,
+  "properties": {
+    "_phase": {
+      "description": "VDD phase that produced this result",
+      "type": "string"
+    },
+    "_sdt": {
+      "description": "Strategy-and-Tactic instructions for the next step",
+      "type": "string"
+    },
+    "artifact": {
+      "description": "Primary artifact produced or returned",
+      "type": "string"
+    },
+    "error": {
+      "description": "Error message when the phase fails",
+      "type": "string"
+    },
+    "gateResult": {
+      "additionalProperties": false,
+      "description": "Quality-gate result, when the phase runs a gate",
+      "properties": {
+        "checks": {
+          "description": "Number of checks run",
+          "type": "number"
+        },
+        "passed": {
+          "description": "Whether the quality gate passed",
+          "type": "boolean"
+        },
+        "total": {
+          "description": "Total number of checks",
+          "type": "number"
+        }
+      },
+      "required": [
+        "passed",
+        "checks",
+        "total"
+      ],
+      "type": "object"
+    },
+    "output": {
+      "additionalProperties": {},
+      "description": "Additional structured phase output",
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "success": {
+      "description": "Whether the phase completed successfully",
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "success",
+    "_phase",
+    "_sdt"
+  ],
+  "type": "object"
+}

First observedv0.1.0Sep 24, 2026

TDQS

A4.6/5.0

Behavior4/5

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

Annotations already declare destructiveHint=true and openWorldHint=false, and the description reinforces this by stating it 'Overwrites these files' and specifying which ones, plus the required pre-existing spec. It does not cover permissions or failure modes, but for a destructive tool with existing annotation coverage this adds meaningful behavioral context.

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?

Single dense paragraph, front-loaded with the action and artifacts, then prerequisites and parameter relationships. Every sentence carries information, though the artifact enumeration makes it longer than strictly minimal.

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?

With an output schema present, return values need not be explained, and the description covers purpose, artifacts, ordering, prerequisites, and parameter continuity. Nothing an agent needs to invoke it correctly is missing.

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 coverage is 100% so the baseline is 3, but the description adds a cross-tool constraint the schema does not: 'feature must match the value passed to vdd_specify and vdd_tasks'. That continuity rule is real value beyond the field-level definitions.

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?

States a specific verb+resource ('Generate the technical blueprint') and enumerates the exact artifacts produced (plan.md, data-model.md, contracts/) plus their location under vdd/specs/<feature>/. Its phase label ('VDD Phase 5') and artifact set clearly distinguish it from vdd_specify, vdd_tasks, and the other siblings.

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?

Explicit ordering guidance: 'run after vdd_specify or vdd_clarify and before vdd_tasks', plus a prerequisite and a fallback ('if no spec exists yet, run vdd_specify first'). It names both the predecessor and successor alternatives, leaving nothing to inference.

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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