mcp-vdd

Generate Plan

vdd_plan

Destructive

Generates technical design docs (plan, data-model, contracts) for a feature under vdd/specs, overwriting existing files. Requires a prior spec; run after vdd_specify or vdd_clarify.

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.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`feature`	Yes	Feature name (spec directory name)
`projectRoot`	No	Project root: directory that constitution.md and the vdd/ folder are written to and resolved against (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.

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

A4.4/5.0

Behavior4/5

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

The annotations already declare destructiveHint=true, and the description adds concrete destructive scope by stating 'Overwrites these files.' It also discloses the prerequisite spec requirement and phase ordering, which goes beyond what annotations alone convey. There is no contradiction with the 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 a single dense sentence with no filler, and the primary action is front-loaded. It packs a lot of important context—outputs, overwrite behavior, preconditions, and phase ordering—into an efficient, readable format, though it could be slightly better organized.

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?

For a destructive generation tool, the description covers all essential context: what files are created, that they are overwritten, the required prerequisite spec, and the correct position in the VDD workflow. Since an output schema exists, return-value details are already handled elsewhere.

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 both 'feature' and 'projectRoot' are already well documented. The description reinforces that 'feature' maps to a directory name under vdd/specs/, but it does not add meaningful parameter semantics beyond what the schema already provides.

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 starts with a specific action ('Generate') and names the exact resource it produces: the technical blueprint under vdd/specs/<feature>/ with plan.md, data-model.md, and contracts/. It also situates itself as 'VDD Phase 5' and references neighboring phases, making it clearly distinguishable from the sibling tools.

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 explicitly states when the tool should be used ('run after vdd_specify or vdd_clarify and before vdd_tasks'), what precondition is required ('Requires an existing spec for the feature'), and what to do if the precondition is not met ('if no spec exists yet, run vdd_specify first').

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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