fynsight: MCP server for DATEV

propose-transaction-correction

Propose a correction to an EXISTING ledger booking — wrong cost center, wrong account, wrong amount, or wrong month. This does NOT change the original booking and does NOT post to the ledger: it creates a PENDING proposal that a human approves in the web app. On approval a reversal of the original booking plus a corrected re-booking are written. Find the transaction id with search_cost_center_transactions first. Use propose-manual-adjustment instead when adding a booking that does not exist yet.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "transaction_id": "<transaction_id>",
      "reason": "<reason>"
    },
    "name": "propose-transaction-correction"
  }
}

Input Schema

Name	Required	Description
`reason`	Yes	Why the booking is corrected; mandatory for the audit trail
`new_amount`	No	New amount, in the same sign convention as the original booking (positive = expense/revenue on that account) — only if the amount changes; 0 means the booking was a duplicate and is only reversed
`new_period`	No	New accounting month (YYYY-MM) — only if the month changes
`new_account`	No	New account — only if the account or its sub-account changes. Notation "4321" or "8400/130". Without a sub-account it is resolved automatically when the account has exactly one variant (the old sub-account is never carried over); if there are several, pass the full account/sub-account.
`transaction_id`	Yes	UUID of the existing booking, from `search_cost_center_transactions`
`new_cost_center`	No	New cost center / Kostenstelle — only if the cost center changes

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 7, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Beyond the annotations (readOnly=false, destructive=false, idempotent=false), the description discloses the crucial non-obvious behavior: it does not mutate the original booking and does not post to the ledger, instead creating a PENDING proposal requiring human approval, after which a reversal plus corrected re-booking are written. This is exactly the kind of deferred-effect semantics an agent could not infer from the flags.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three front-loaded sentences: purpose and scope first, behavioral consequence second, routing and prerequisite last. Every clause carries information — the em-dash examples map directly to the optional parameters and the negatives preempt the most likely misuse.

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 6-parameter mutation tool with no output schema, the description covers the full lifecycle an agent needs: how to obtain the id, what the call actually creates, that a human approves it, and what is written on approval. Nothing essential is left to inference.

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 coverage is 100% and the per-field descriptions are already exhaustive (sign convention, '0 means duplicate', sub-account resolution rules). The description only restates the field list as correction scenarios (cost center, account, amount, month) without adding format or constraint detail, so the baseline 3 applies.

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 and resource ('Propose a correction to an EXISTING ledger booking') and enumerates the four correction types it covers. It explicitly distinguishes itself from both `search_cost_center_transactions` (id lookup) and `propose-manual-adjustment` (new bookings), so an agent can route correctly without opening schemas.

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?

Gives an explicit when-not rule ('Use `propose-manual-adjustment` instead when adding a booking that does not exist yet') and an explicit prerequisite ('Find the transaction id with `search_cost_center_transactions` first'). The exclusions and ordering are both spelled out rather than implied.

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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