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patthewebrat

xero-oauth-mcp-server

by patthewebrat

xero-oauth-mcp-server

A custom Model Context Protocol server for Xero, using the standard OAuth2 authorization-code + refresh-token flow (no paid Custom Connection required). Supports multiple connected organisations (tenants) — every tool takes an optional org argument.

Capabilities

  • Contacts: list_contacts, get_contact, create_contact, update_contact

  • Invoices: list_invoices, get_invoice, get_invoice_pdf, download_invoice_pdfs, create_invoice, update_invoice, list_overdue_invoices, list_recurring_invoices

  • Utility: list_organisations, list_accounts

Related MCP server: Xero MCP Server

How org selection works

Each tool accepts an optional org. It is resolved (case-insensitive) against:

  1. an alias from XERO_ORG_ALIASES (e.g. main → a tenantId),

  2. an exact tenantId, then

  3. a substring of the org's name in Xero.

If org is omitted, the server uses XERO_DEFAULT_ORG (which may itself be an alias), or the first connected org when that is unset.

One-time setup

1. Create a Xero app

developer.xero.comNew app → Web app.

  • Add redirect URI: http://localhost:49831/callback

  • Copy the Client ID and generate a Client Secret.

Newer Xero apps use granular scopes. This server requests accounting.contacts, accounting.invoices, and accounting.settings.read (plus openid profile email offline_access). Make sure those are enabled on the app.

2. Build

npm install
npm run build

3. Authorize (interactive, once)

XERO_CLIENT_ID=xxx XERO_CLIENT_SECRET=yyy npm run auth

A browser opens — log in and authorize each organisation you want to use (re-run to add more later). The refresh token and the connected tenant list are saved to ~/.xero-mcp-id/tokens.json (chmod 600). The refresh token rotates automatically on every use.

4. Register with an MCP client

Example (Claude Code):

claude mcp add xero -s user \
  -e XERO_CLIENT_ID=xxx \
  -e XERO_CLIENT_SECRET=yyy \
  -e XERO_DEFAULT_ORG=main \
  -e XERO_ORG_ALIASES='{"main":"<tenant-guid>","secondary":"<tenant-guid>"}' \
  -- node /absolute/path/to/dist/index.js

Environment variables

Var

Default

Purpose

XERO_CLIENT_ID / XERO_CLIENT_SECRET

App credentials (required)

XERO_DEFAULT_ORG

first org

Org used when a tool omits org (alias/tenantId/name)

XERO_ORG_ALIASES

{}

JSON map of friendly alias → tenantId

XERO_REDIRECT_PORT

49831

Local callback port (must match the app's redirect URI)

XERO_PDF_DIR

~/Downloads

Where the PDF tools save files when no path is given

XERO_READONLY

unset

When true, all write tools refuse

XERO_TOKEN_DIR

~/.xero-mcp-id

Where the token store lives

Security

  • No credentials or tokens are stored in this repository.

  • Client ID/secret are passed via environment; the refresh token + tenant list live only in XERO_TOKEN_DIR (default ~/.xero-mcp-id/, chmod 600), which is git-ignored.

  • Write tools (create_* / update_*) can be globally disabled with XERO_READONLY=true.

License

MIT

Available Tools

12 tools
create_contactC

[WRITE] Create a new contact.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
nameYesContact name (required, must be unique in the org).
firstNameNo
lastNameNo
emailAddressNo
phoneNoDefault/mobile phone number.
rawNoAdvanced: extra Xero Contact fields merged into the body.

TDQS

C2.6/5.0
Behavior2/5

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

No annotations provided, so the description carries full burden. It does not disclose required permissions, side effects (e.g., uniqueness constraints on 'name'), or any behavioral traits beyond the basic creation action. The '[WRITE]' tag hints at write operation but adds little detail.

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

Conciseness3/5

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

Extremely concise (single line), but at the cost of missing essential details. The '[WRITE]' prefix provides some structure, but the description is too terse to be fully informative.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 7 parameters, no output schema, and no annotations, the description is incomplete. It does not explain return values, error conditions, or the expected behavior of the 'raw' parameter. Missing context for real-world usage.

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

Parameters2/5

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

The description does not add any meaning beyond the input schema, which has 57% coverage. Parameters like 'firstName' and 'lastName' lack schema descriptions, and the tool description does not compensate. The 'raw' object is mentioned as 'Advanced' but not further explained.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action 'Create a new contact,' which is a specific verb+resource. It distinguishes from siblings like 'create_invoice' and 'update_contact.' However, it lacks additional context like what type of contact (e.g., customer, supplier).

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

Usage Guidelines2/5

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

No guidance on when to use this tool versus alternatives (e.g., 'update_contact' for modifications). There is no mention of prerequisites or scenarios where creation might fail.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

create_invoiceB

[WRITE] Create an invoice (sales ACCREC by default). Defaults to DRAFT status.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
typeNoACCREC=sales, ACCPAY=bill.
contactIdNoExisting contactID (preferred).
contactNameNoContact name (used if no contactId).
lineItemsYes
dateNoYYYY-MM-DD.
dueDateNoYYYY-MM-DD.
referenceNo
statusNoDefaults to DRAFT.
lineAmountTypesNo
rawNoAdvanced: extra Invoice fields.

TDQS

B3.4/5.0
Behavior2/5

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

No annotations are provided, so the description bears the full burden. It indicates the tool is a write operation with '[WRITE]' and mentions default status, but lacks details on idempotency, authentication requirements, rate limits, or side effects (e.g., whether it modifies other resources).

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?

The description is a single sentence with no unnecessary words. It is front-loaded with '[WRITE]', making the action clear immediately.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has 11 parameters, nested objects, and no output schema, the description is too brief. It does not explain return values, error handling, or advanced usage patterns, leaving many aspects undocumented.

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?

The schema already covers 73% of parameters with descriptions. The description adds value by clarifying default values for 'type' (ACCREC) and 'status' (DRAFT), which are not fully captured in the schema. However, it does not explain complex parameters like 'raw' or 'tracking' further.

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 clearly states the verb 'Create', the resource 'invoice', and adds specifics: defaults to sales (ACCREC) and DRAFT status. This distinguishes it from sibling tools like 'update_invoice' and 'list_invoices'.

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

Usage Guidelines2/5

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

The description provides no explicit guidance on when to use this tool versus alternatives (e.g., when to use ACCPAY vs ACCREC, or when to use update_invoice instead). The schema includes an enum for type, but the description does not help with decision-making.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

get_contactA

Get a single contact by its contactID.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
contactIdYesThe Xero contactID (GUID).

TDQS

A3.5/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden. It only states 'Get a single contact', with no mention of side effects (none expected), auth requirements, rate limits, or return format. A read-only hint would improve transparency.

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?

The description is a single sentence, front-loaded with the core purpose, and contains no extraneous information. It is highly concise.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple lookup tool with two parameters and no output schema, the description is minimally complete. It could be improved by noting that the full contact object is returned, but overall it is adequate given the low complexity.

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 description coverage is 100% (both parameters described). The description adds 'by its contactID' which echoes the contactId schema description. It does not provide additional context for the 'org' parameter beyond what the schema already states.

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 clearly states the action ('Get'), the resource ('a single contact'), and the method ('by its contactID'). It distinguishes from list_contacts (which retrieves many) and create/update contacts.

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

Usage Guidelines3/5

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

The description implies use when you have a specific contactID, but does not explicitly state when to use this tool versus list_contacts or alternatives like update_contact. No when-not-to-use or prerequisite guidance is provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

get_invoiceA

Get a single invoice (with line items) by invoiceID or invoice number.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
invoiceIdNoThe Xero invoiceID (GUID).
invoiceNumberNoThe invoice number, e.g. INV-0042.

TDQS

A4/5.0
Behavior3/5

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

No annotations provided; description adds 'with line items' but does not disclose read-only nature, authentication requirements, or error handling. Minimum viable for a simple read operation.

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?

Single sentence, no redundant information, highly efficient. Every word is purposeful.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple retrieval tool with no output schema, description covers the core functionality and return inclusion (line items). Could mention full object return, but sufficient given sibling context.

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% with descriptions for each parameter. Description adds little beyond restating that you can look up by invoiceId or invoiceNumber, which schema already covers. Baseline 3.

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?

Clear verb 'get' plus specific resource 'single invoice (with line items)' and identification methods (by invoiceID or invoice number). Distinguishes from sibling like list_invoices which returns multiple invoices.

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?

Implies usage when you need one invoice by ID/number, but no explicit when-not to use or comparison to alternatives. Adequate but not explicit.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_accountsA

List the chart of accounts (codes, names, types, tax types) for an org — useful before creating invoices.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
whereNoOptional Xero filter, e.g. 'Class=="REVENUE"'.

TDQS

A4.2/5.0
Behavior3/5

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

No annotations provided, so description carries full burden. It states 'list' implying read-only, but does not disclose potential errors, pagination, or idempotency. Basic coverage adequate for simple list operation.

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?

Single sentence with essential information, no wasted words. Front-loads the primary action and result, with a brief usage hint.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple list tool with 2 parameters and no output schema, the description covers the main purpose and parameter usage. Lacks details on return structure or errors, but sufficient for the tool's complexity.

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 coverage is 100% with descriptions, but the tool description adds meaning: explains org parameter defaults and alias usage, gives an example for the where filter. Adds value beyond schema fields.

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?

Clearly states it lists the chart of accounts with specific fields (codes, names, types, tax types). Distinguishes from sibling tools like list_contacts or list_invoices by targeting accounts, and adds context 'useful before creating invoices'.

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?

Indicates usefulness before creating invoices but does not explicitly state when not to use or mention alternatives. Context is clear, but no exclusions or comparisons to sibling list tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_contactsB

List/search contacts in an org.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
searchTermNoFree-text search across name/email.
whereNoXero filter, e.g. 'IsCustomer==true'.
pageNoPage number (100/page).
includeArchivedNo

TDQS

B3.2/5.0
Behavior2/5

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

No annotations. Description does not disclose pagination, read-only nature, or effect of searchTerm vs where. Behavioral details are implied but not explicit.

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?

Single sentence, no filler, front-loaded with purpose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema; description does not explain return format, pagination, or default behavior. Incomplete for a read tool with 5 params.

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 80%, description does not add meaning beyond schema. Baseline 3 is appropriate.

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?

Description states 'List/search contacts in an org.' - clear verb and resource, distinct from get_contact (single) and create_contact.

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

Usage Guidelines2/5

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

No guidance on when to use list vs search vs get, or alternatives. No exclusionary context provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_invoicesC

List/search invoices in an org. Filter by status, contact, invoice number, or a raw Xero filter.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
statusesNo
contactIdsNo
invoiceNumbersNo
whereNoRaw Xero filter expression.
orderNoe.g. "DueDate ASC".
pageNoPage number (100/page).

TDQS

C2.9/5.0
Behavior2/5

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

No annotations are provided, so the description must disclose behavioral traits itself. It only states 'List/search' implies a read operation, but provides no details on pagination, rate limits, or side effects. The page parameter suggests pagination, but this is not explained in the description.

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

Conciseness4/5

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

The description is a single concise sentence that front-loads the main purpose. It is clear and avoids unnecessary words. Minor improvement could be made by adding structure or bullet points for readability, but overall it is efficient.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 7 parameters and no output schema, the description is insufficient. It lacks details on pagination, ordering, filtering syntax (e.g., raw Xero filter), and expected return values. The tool has moderate complexity, yet the description provides only a high-level overview.

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 description coverage is 57%, and the description adds some context by summarizing filterable fields (status, contact, invoice number, raw filter). However, it does not elaborate on order, page, or org parameter semantics beyond what the schema already provides. The description partially compensates for coverage gaps but could be more complete.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('List/search') and resource ('invoices') within an org, and mentions filtering options. However, it does not explicitly distinguish this tool from siblings like 'list_overdue_invoices' or 'list_recurring_invoices', which would help the agent choose correctly.

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

Usage Guidelines2/5

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

There is no guidance on when to use this tool versus alternatives, nor any prerequisites or exclusions. The description omits any mention of the sibling tools that might be more appropriate for specific invoice subsets (overdue, recurring).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_organisationsA

List the connected Xero organisations (orgs) and the default one.

ParametersJSON Schema
NameRequiredDescriptionDefault

No parameters

TDQS

A4.3/5.0
Behavior3/5

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

No annotations provided, so description must carry the burden. It discloses that the tool lists organisations and the default one, but does not mention authentication requirements, rate limits, or any potential side effects. For a read-only listing tool, the description is minimally adequate.

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?

Description is a single concise sentence that directly conveys the tool's purpose with no unnecessary words. It is front-loaded and efficient.

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?

Given no parameters and no output schema, the description is complete enough for an agent to understand what the tool returns. It clearly differentiates from sibling tools and sets correct expectations.

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?

Input schema has zero parameters, so baseline is 4. The description adds value beyond the schema by specifying that it lists 'connected' organisations and indicates the default one, providing semantic context.

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?

Description clearly states that the tool lists connected Xero organisations and identifies the default one. It uses specific verb 'list' and resource 'organisations', and distinguishes from sibling tools which focus on contacts, invoices, and accounts.

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?

No explicit when-to-use or when-not-to-use guidance, but the purpose is obvious given the tool's simplicity and the sibling tools' focus on different entities. The description implies usage for retrieving connected organisations.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_overdue_invoicesA

List overdue sales (ACCREC) invoices: AUTHORISED, past due date, with an outstanding balance.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
orderNoDefaults to "DueDate ASC".

TDQS

A3.6/5.0
Behavior2/5

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

No annotations provided, so description carries full burden. It describes the criteria but does not mention pagination, side effects, rate limits, or that it's a read-only operation. Lacks detail on behavioral traits.

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?

Single sentence with efficient use of colons to add detail. No wasted words, front-loaded with the core action.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple list tool with 2 parameters and no output schema, the description is mostly complete, specifying criteria. Minor gaps: no mention of pagination, result format, or rate limits, but adequate for typical use.

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% for both 'org' and 'order' parameters. The description adds no extra semantics beyond what the schema already provides, so baseline 3 is appropriate.

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 clearly states 'List overdue sales (ACCREC) invoices' with specific criteria (AUTHORISED, past due date, outstanding balance), distinguishing it from 'list_invoices' which likely lists all invoices.

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

Usage Guidelines3/5

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

The description implies use when overdue invoices are needed, but does not explicitly state when to use this vs alternatives like 'list_invoices'. No exclusions or prerequisites are mentioned.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

list_recurring_invoicesC

List repeating (recurring) invoice templates in an org.

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
whereNo
orderNo

TDQS

C2.9/5.0
Behavior2/5

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

With no annotations, the description carries full burden. It only states the basic action, omitting behavioral traits like read-only nature, authentication needs, or pagination. This is insufficient for safe invocation.

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

Conciseness3/5

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

The single-sentence description is efficient but lacks necessary details, making it under-informative rather than appropriately concise.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given three parameters, no output schema, and no annotations, the description is incomplete. It does not explain output format, parameter usage (e.g., 'where', 'order'), or any prerequisites.

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

Parameters2/5

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

Schema coverage is only 33%; the description adds no meaning beyond the schema. The 'where' and 'order' parameters remain unexplained, failing to compensate for low coverage.

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 'List repeating (recurring) invoice templates in an org' clearly states the verb (list), resource (recurring invoice templates), and scope (in an org). It effectively distinguishes from sibling tools like list_invoices.

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

Usage Guidelines2/5

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

No guidance is provided on when to use this tool versus alternatives such as list_invoices or create_invoice. There are no context or exclusions given.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

update_contactA

[WRITE] Update an existing contact (only supplied fields change).

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
contactIdYesThe Xero contactID (GUID) to update.
nameNo
firstNameNo
lastNameNo
emailAddressNo
phoneNo
contactStatusNoSet ARCHIVED to archive the contact.
rawNoAdvanced: extra Contact fields.

TDQS

A3.8/5.0
Behavior3/5

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

No annotations provided, so description carries all burden. It discloses the write nature via [WRITE] and partial update behavior, but lacks details on permissions, side effects of archiving, or response format.

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?

Single sentence, front-loaded with [WRITE] indicator, no fluff. Every word earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 9 parameters, nested objects, no output schema, and no annotations, the description is too terse. Missing: return value, error conditions, prerequisite that contact must exist, workflow context among siblings.

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 description coverage is 44%, so description must add value. The phrase 'only supplied fields change' clarifies that all optional parameters behave as partial updates, which goes beyond schema. However, individual parameter meanings are not elaborated.

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?

Description clearly states the tool updates an existing contact, with verb 'Update' and resource 'contact'. It distinguishes from sibling create_contact and get_contact by specifying it modifies an existing entity.

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?

Implied usage when modifying an existing contact's fields. Does not explicitly exclude other scenarios or list alternatives, but the purpose is clear enough for selection.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

update_invoiceB

[WRITE] Update an invoice by invoiceID (e.g. change status, reference, due date, or line items).

ParametersJSON Schema
NameRequiredDescriptionDefault
orgNoOrg to target: a tenantId, a tenant-name substring, or an alias from XERO_ORG_ALIASES. Defaults to the first connected org.
invoiceIdYesThe Xero invoiceID (GUID) to update.
statusNo
referenceNo
dueDateNoYYYY-MM-DD.
dateNoYYYY-MM-DD.
lineItemsNoReplaces the line items if supplied.
rawNoAdvanced: extra Invoice fields.

TDQS

B3.2/5.0
Behavior2/5

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

No annotations provided, so description is the sole source. Only indicates it's a write operation via '[WRITE]'. No details on side effects, permissions, or state constraints (e.g., can you update a VOIDED invoice?).

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?

Single sentence, no fluff. Front-loaded with '[WRITE]' for quick classification. Efficient for its length.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 8 parameters, nested objects, and no output schema, the description is too brief. It omits return value, error handling, required permissions, and behavior when invoice is in certain states. Insufficient for a complex tool.

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 75% (most parameters have descriptions). The description adds value by summarizing updatable fields but does not elaborate on parameter semantics beyond the schema. For instance, 'lineItems' says 'Replaces the line items if supplied' in schema, but description doesn't expand.

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?

Clearly states the action 'Update an invoice by invoiceID' with examples (status, reference, due date, line items). Distinguishes from siblings like create_invoice (write) and get_invoice (read).

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

Usage Guidelines2/5

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

No explicit guidance on when to use vs alternatives. Does not mention prerequisites or when not to use (e.g., invoice already voided). Context only implied by examples.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

  1. 12 tool updatesv0.1.0
    • First observedcreate_contact
    • First observedcreate_invoice
    • First observedget_contact
    • First observedget_invoice
    • First observedlist_accounts
    • First observedlist_contacts
    • First observedlist_invoices
    • First observedlist_organisations
    • First observedlist_overdue_invoices
    • First observedlist_recurring_invoices
    • First observedupdate_contact
    • First observedupdate_invoice

TDQS

A3.6/5.0

Scored across 12 tools

Disambiguation5/5

Each tool targets a distinct resource and action (contact, invoice, accounts, etc.). Even specialized invoice tools like list_overdue_invoices and list_recurring_invoices have clear names that prevent ambiguity.

Naming Consistency5/5

All tools follow a consistent verb_noun pattern (create_*, get_*, list_*, update_*), making it predictable and easy for an agent to infer purpose from the name.

Tool Count5/5

With 12 tools covering core CRUD for contacts and invoices plus useful listing filters, the set is well-scoped for a Xero accounting API server—neither too sparse nor too overwhelming.

Completeness4/5

Covers the main workflows for contacts and invoices (create, read, update, list) with additional filters. Missing delete operations and account creation/update, but these are often handled externally or are less critical for basic usage.

Maintenance

ActivityMaintained
ResponsivenessNo issues

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