Phase 3 — The data-model guide

[gilgardosh]

No description provided.

[Copilot]

Pull request overview

Adds a “data-model guide” discovery tool to the MCP server so agents can read a canonical, code-checked explanation of Accounter’s accounts/charges model (and common aggregation traps) before querying and interpreting business data.

Changes:

• Introduces accounter_data_model_guide as a pure, no-scope, read-only tool that returns a static markdown guide plus structured { guide, version }.
• Registers the guide immediately after membership discovery so it appears early in tools/list.
• Adds tests to prevent guide drift (tool-name references, charge/account types, prompt budget) and updates docs to reflect the new tool count and behavior.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/mcp-server/src/tools/registry-instance.ts	Registers the new guide tool early in registry order (right after memberships).
packages/mcp-server/src/tools/data-model-guide.ts	Implements the static guide tool and exports guide/version constants.
packages/mcp-server/src/tools/tests/scope-forwarding.test.ts	Treats the new guide as a pure tool in scope-forwarding assertions.
packages/mcp-server/src/tools/tests/data-model-guide.test.ts	Adds purity + drift-prevention tests and prompt-size budget checks.
packages/mcp-server/README.md	Documents the new tool and updates curated tool count.
packages/mcp-server/docs/todo.md	Updates the stated curated tool count.
docs/mcp-extension/plan.md	Marks Phase 3 as done and documents implementation notes.

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