lago_list_feesList fees, optionally filtered by customer, subscription, or fee type. Lago API: GET /fees.
| Name | Required | Description | Default |
|---|---|---|---|
| page | No | Page number for pagination. | |
| fee_type | No | Filter by fee type: charge | add_on | subscription | credit | commitment. | |
| per_page | No | Number of records per page. | |
| external_customer_id | No | Filter by customer external id. | |
| external_subscription_id | No | Filter by subscription external id. |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already provide readOnlyHint=true. Description adds API endpoint and filtering capability. No extra behavioral context beyond what annotations convey.
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 concise sentences: first states purpose and filtering, second provides API reference. No wasted words.
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?
Adequate for a list tool with no output schema. Covers key aspects; could mention pagination but schema already defines page/per_page parameters.
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 has 100% description coverage for all 5 parameters. Description reiterates filtering by customer, subscription, or fee type, adding marginal value.
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?
Description clearly states it lists fees with optional filters by customer, subscription, or fee type. Includes API endpoint. Distinct from sibling list tools.
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?
Description mentions optional filtering but does not provide explicit guidance on when to use this tool versus other list tools or what filters are appropriate.
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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