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sarathfrancis90

splitwise-mcp

create_expense

Create an expense split evenly, by exact amounts, percentages, or shares among a group or friend.

Instructions

Create a new expense, split among a group or with a single friend.

Exactly one of group_id/group_name or friend_id/friend_name must be given. Every participant in split must be resolvable, by id or by name, against that group's members (for a group expense) or against the authenticated user plus their friends (for a friend expense).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
dateNoDate the expense occurred. Defaults to now. A value with no timezone is treated as UTC.
splitYesHow to divide the expense among its participants.
amountYesTotal cost of the expense.
group_idNoId of the group this expense belongs to.
payer_idNoId of who paid. Defaults to the authenticated user.
friend_idNoId of the friend to split this expense with, for a non-group expense.
group_nameNoName (or partial name) of the group this expense belongs to.
payer_nameNoName (or partial name) of who paid.
category_idNoId of the expense's category.
descriptionYesShort human-readable description of the expense.
friend_nameNoName (or partial name) of the friend to split this expense with.
category_nameNoName (or partial name) of the expense's category.
currency_codeYesISO 4217 currency code, e.g. 'USD'.
allow_duplicateNoSet true to create this expense even if a matching one was created in the last two minutes.
idempotency_keyNoOpaque key identifying this logical write. Reusing it replays the original result instead of creating a second expense.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
idYesSplitwise's numeric id for this expense.
costYesTotal cost of the expense, in currency_code units.
dateYesDate and time the expense occurred.
splitsNoPer-participant owed and paid shares for this expense.
deletedNoWhether this expense has been soft-deleted in Splitwise.
categoryNoCategory assigned to this expense, if any.
group_idNoId of the group this expense belongs to, if any.
descriptionYesShort human-readable description of the expense.
currency_codeYesISO 4217 currency code the cost is denominated in.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. First observedv0.1.0

TDQS

A4.5/5.0
Behavior4/5

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

Annotations already indicate readOnlyHint=false, so the write nature is covered. The description adds genuinely useful behavioral context beyond annotations: the exclusive group/friend requirement and how participant names are resolved against group members or the authenticated user's friends.

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?

Two tight paragraphs with no filler. The first sentence front-loads the action and scope, and every subsequent sentence conveys a constraint an agent must know to call the tool successfully.

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 15-parameter tool with complete schema descriptions and an output schema, the description covers the two non-obvious invariants that would otherwise cause failed calls: the exclusive group/friend target and participant resolvability. Required parameters and defaults are already documented in the schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description adds value by expressing the exactly-one constraint among group_id/group_name/friend_id/friend_name and explaining how name-based participant resolution works—semantics not captured by the schema's individual parameter descriptions.

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?

The description names the exact operation (create), the resource (expense), and the scope (split among a group or a single friend). This clearly differentiates it from sibling tools like get_expense, update_expense, and delete_expense without needing to inspect the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly establishes the creation context and states the hard constraint that exactly one group or friend identifier must be provided. It doesn't explicitly name alternative tools for when not to use it, but the verb 'Create' plus the resource makes the use case unambiguous.

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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