Record an expense purchase in KikoBooks by providing expense date, line items, amounts, and expense accounts.
Create a purchase (expense) in KikoBooks. Requires expense date and line items with amounts and expense accounts.
| Name | Required | Description | Default |
|---|---|---|---|
| purchase | Yes |
Changes observed during successful MCP inspections.
v0.2.9Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations at all, the description carries the full behavioral burden for a mutation tool and largely fails to: it does not say whether the purchase is created as draft or posted, what the accounting side effects are, what happens if accountId or paymentAccountId are omitted, or whether vendorId is required in practice. The only added context is the purchase/expense equivalence, which is thin for a write operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two tight sentences with the core verb/resource front-loaded and no filler. It is efficiently written; the issue is underspecification rather than verbosity.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a nested-object mutation tool with no annotations and no output schema, the description should explain permissions, draft/posted behavior, and the account-field semantics. None of that is present, leaving an agent with only the schema to infer how to build a valid, correctly-categorized purchase.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is reported at 0%, so the description is expected to compensate, but it only restates that line items need amounts and 'expense accounts'. It never clarifies the critical distinction between lineItems.accountId (expense GL account) and purchase.paymentAccountId (bank/cash account), nor the role of vendorId, taxCode, or referenceNumber.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource ('Create a purchase') and disambiguates the domain term with the parenthetical '(expense)'. It does not differentiate itself from adjacent write siblings like create_bill or create_invoice, but the purpose itself is unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The second sentence lists required inputs ('expense date and line items'), which is a prerequisite rather than usage guidance, and that fact is already in the schema. There is no statement of when to create a purchase versus a bill or credit memo, nor any precondition such as a required vendor or connection state.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.