Decline a pending invoice by providing its ID and a reason. Use this to reject invoices in Deel's system.
Decline a pending invoice with a reason.
| Name | Required | Description | Default |
|---|---|---|---|
| reason | Yes | Reason for declining the invoice | |
| invoice_id | Yes | The invoice ID to decline |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The only annotation is a title, so the description carries the full behavioral burden for a mutation tool. It says nothing about whether a decline is reversible, what status the invoice moves to, whether a reason is surfaced to the counterparty, or what permissions are required.
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?
One short sentence with the action and its required input front-loaded and no filler. It is efficient, though arguably too terse to be maximally useful.
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 destructive-leaning mutation with no annotations and no output schema, the description should disclose reversibility, resulting state, and permission expectations. None of that is present, leaving an agent guessing about consequences.
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 100% with both parameters documented, so the baseline is 3. The phrase 'with a reason' confirms the required reason parameter but adds no format, length, or content guidance beyond the schema.
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 ('Decline') and resource ('invoice') with a scope qualifier ('pending'), which cleanly separates it from approve_invoice and get_invoice in the sibling list. It stops short of explicitly naming those alternatives, so it is clear but not fully differentiated.
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?
'Pending' implies a precondition — only invoices in that state can be declined — but the description never states when to choose this over approve_invoice or what to do with a non-pending invoice. Usage is inferable rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.