Files
accounted/extensions/general/mcp-server
523beaa18b fix(mcp): give the missing-chart-accounts refusal a code agents can dispatch on (#2075)
getStructuredError resolves an error with no `code` to UNKNOWN_ERROR, whose
registry text is the constant "Något gick fel. Försök igen." So an agent
branching on `code` saw "unknown" for a failure whose own message already
named the accounts and the two tools that fix it.

On production that was 40 of the create_voucher failures in 60 days.

Everything needed already existed: the ACCOUNTS_NOT_IN_CHART code, its
registry entry, its remediation pointing at the chart-of-accounts resource,
and a typed error class that storno-service already throws. This path just
never attached the code.

Attached with Object.assign rather than by throwing AccountsNotInChartError,
because that class builds its own generic English message from the account
list and would discard the richer Swedish one, which is the more useful half.

Pinned by a test asserting the same message WITHOUT the code still resolves to
UNKNOWN_ERROR, so this cannot silently regress.

Not fixed here: the MCP server has ~155 bare Swedish-prose throws against 3
uses of codedError(), so most domain failures remain undispatchable. This
fixes the one instance telemetry actually proved rather than converting 155
sites blind.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-31 22:01:27 +02:00
..
2026-07-24 15:03:50 +02:00
2026-07-24 15:03:50 +02:00

Accounted MCP server

JSON-RPC 2.0 server exposing the Accounted bookkeeping engine to MCP clients (Claude Desktop, Claude Code, etc.). Endpoint: /api/extensions/ext/mcp-server/mcp. Add ?tool_namespace=accounted for the Accounted tool names. Requests without it retain the legacy Gnubok namespace. OAuth and stdio bridges live alongside the API surface: see app/api/mcp-oauth/, packages/accounted-mcp/, and the compatibility package in packages/gnubok-mcp/.

Tool authoring contract

Enforced by tests in __tests__/: these are not style preferences, they're guard rails.

  1. additionalProperties: false on every inputSchema. Guarded by strict-schemas.test.ts. Forces clear rejections on hallucinated fields instead of silent ignores.
  2. Descriptions ≤ 280 chars. Guarded by output-schema.test.ts. No Args: / Returns: / Examples: prose: those belong in JSON Schema. Use agent-native hints ("Use to…", "Call X first", "HIGH risk").
  3. Staged-operation envelope for write tools: outputSchema: STAGED_OPERATION_SCHEMA (server.ts). Fields: staged, risk_level, actor, message, preview, period_status?, next?. The staged: true boolean is the explicit completion signal; agents must not infer completion from prose. Do NOT introduce a parallel { success, shouldContinue, output } envelope.
  4. period_status threading: any tool that ties to a fiscal-period-bound date (categorize, mark paid, create voucher, correct/reverse entry, approve supplier invoice) passes dateForPeriodCheck to stagePendingOperation. Response then includes period_status: { period_id, status: open|locked|closed, lock_date } so widgets and agents disable writes without round-trips.
  5. Scope mapping: every new tool needs an entry in lib/auth/api-keys.ts TOOL_SCOPE_MAP. Missing entries default to deny.
  6. Tests for new write tools: add staging-gate coverage to __tests__/voucher-tools.test.ts (or a sibling) plus executor coverage to lib/pending-operations/__tests__/voucher-executors.test.ts if the tool stages a new operation_type.

Determinism / cache stability

Tool definitions (name, description, inputSchema, outputSchema, annotations) are declared as static object literals at module load: no timestamps, no UUIDs, no Date/Math.random in the definition layer. This makes the tools/list JSON payload byte-stable across requests, which lets agent-side prompt caches stay warm. Do not introduce per-request non-determinism into the definitions block. Anything time-bound or random belongs inside execute().

For internal Anthropic API usage (the SDK is called from lib/ai/provider.ts and lib/ai/services/anthropic-family.ts; features such as extensions/general/invoice-inbox/lib/extract-invoice-fields.ts go through getAiService() in lib/ai rather than the SDK directly): annotate stable prefixes with cache_control: { type: 'ephemeral' } and log usage.cache_read_input_tokens for hit-ratio observability. The 1h TTL from the agent-native API plan (item 10) requires the direct Anthropic API; Accounted's Bedrock path defaults to a shorter TTL.

Payload-size watchdog

payload-size.bench.test.ts enforces a tools/list JSON payload ceiling. If the test fires, the right answer is rarely "raise the ceiling". Instead, trim descriptions or set specialized wide tools to catalogVisibility: 'search'. Those tools remain discoverable with full schemas through gnubok_search_tools and callable through tools/call on the wire without bloating the default catalog. Claude.ai only calls tools present in tools/list, so a tool that a user or a skill must call directly stays in the default catalog.

Where things live

  • server.ts: the tools array + JSON-RPC dispatcher
  • tool-result.ts: withNext(), toToolError() response helpers
  • resources/: read-only Accounted:// URIs, registered in resources/index.ts: company/current, period/active, recent-activity, capabilities, attention, chart-of-accounts, settings/vat-treatments, booking-templates, ledger/context, reconciliation/summary
  • widgets/: inline HTML widgets (receipt-matcher, vat-review, pending-operations)
  • prompts/: slash-command-style prompts
  • skills/: domain-knowledge skill bodies served via gnubok_load_skill
  • public-tools.ts: lazy authentication (issue #1814). ANONYMOUS_METHODS (initialize, ping, tools/prompts/resources listing) and the three PUBLIC_TOOLS (gnubok_search_tools, gnubok_list_skills, gnubok_load_skill) answer without credentials, rate-limited per truncated IP; every other tools/call gets a transport-level 401 + WWW-Authenticate from handleMcpRequest in server.ts, which is the challenge clients turn into their Connect prompt
  • tasks.ts: MCP Tasks extension (io.modelcontextprotocol/tasks): durable handles for long-running tool calls, rows in mcp_tasks (service-role writes only)
  • origin-guard.ts: Origin-header validation on the Streamable HTTP endpoint (DNS-rebinding defence required by the MCP spec)
  • staging-pii-guard.ts: refuses a plaintext personnummer in staged pending_operations params/preview, so every staging tool inherits the encrypt-at-staging rule
  • tool-namespace.ts: ?tool_namespace=accounted handling (accounted_* aliases for the canonical gnubok_* ids)
  • __tests__/: strictness guards + per-tool coverage