treasury-fiscaldata-mcp-server: Instructions file for Claude Code

Developer Protocol

Server: @cyanheads/treasury-fiscaldata-mcp-server Version: 0.1.10 Framework: @cyanheads/mcp-ts-core ^0.12.3 Engines: Bun ≥1.3.0, Node ≥24.0.0 MCP SDK: @modelcontextprotocol/server ^2.0.0 (+ @modelcontextprotocol/client ^2.0.0 for client-side test code) Zod: ^4.4.3

Read the framework docs first: node_modules/@cyanheads/mcp-ts-core/CLAUDE.md contains the full API reference — builders, Context, error codes, exports, patterns. This file covers server-specific conventions only.

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Server Overview

Tools (7):

Tool	Purpose
treasury_list_datasets	Browse curated catalog of 17 Treasury Fiscal Data endpoints
treasury_query_dataset	Query any endpoint by path, fields, filters, sort, page — with optional DataCanvas spill
treasury_get_debt	National debt (Debt to the Penny) — latest, specific date, or date-range series
treasury_get_interest_rates	Average Treasury interest rates by security type (monthly)
treasury_get_exchange_rates	Official statutory exchange rates for ~165 countries (quarterly)
treasury_dataframe_describe	List DataCanvas dataframes with schema, row count, and TTL
treasury_dataframe_query	Run single-statement SELECT against DataCanvas dataframes via DuckDB

Services:

• fiscal-data — Treasury Fiscal Data API client with embedded endpoint catalog
• canvas-bridge — Adapter over framework DataCanvas: df_<id> minting, per-table TTL, system-catalog SQL deny

DataCanvas: requires CANVAS_PROVIDER_TYPE=duckdb. All Treasury columns are VARCHAR — CAST to DECIMAL or DATE for arithmetic.

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Core Rules

• Logic throws, framework catches. Tool/resource handlers are pure — throw on failure, no try/catch. Plain Error is fine; the framework catches, classifies, and formats. Use error factories (notFound(), validationError(), etc.) when the error code matters.
• Use ctx.log for request-scoped logging. No console calls.
• Use ctx.state for tenant-scoped storage. Never access persistence directly.
• Need input the caller didn't supply? return ctx.requestInput(...) and read ctx.inputs when the handler is re-entered. Never await for user input mid-handler.
• Tool inputs are strict. An undeclared root key is rejected by name rather than stripped; a nested object strips unless it is marked .strict() itself. error is reserved on output and enrichment — it is the wire's failure envelope, and tool() throws at definition time on either.
• Secrets in env vars only — never hardcoded.
• Close the loop on issues. When implementing work tracked by a GitHub issue, comment on the issue with what landed and close it. Do both — a comment without a close leaves stale issues open; a close without a comment leaves no record of what shipped. The comment is for future readers — state the concrete changes, not the conversation that produced them.