libby-mcp

return_loan

Destructive

Returns a borrowed library ebook or audiobook early using its OverDrive title ID; confirm with the user before proceeding.

Instructions

Return a loan early. Confirm with the user first.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "title_id": "<title_id>"
    },
    "name": "return_loan"
  }
}

Input Schema

Name	Required	Description	Default
`library`	No	Library key of the card to use; optional with a single linked card.
`title_id`	Yes	OverDrive title id the library owns.

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 23, 2026

TDQS

A3.8/5.0

Behavior4/5

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

Annotations already flag destructiveHint=true and openWorldHint=true, so the safety profile is covered. The description adds a critical behavioral requirement: confirm with the user before acting. It could say more about reversibility or effects on history, but it adds meaningful context beyond the annotations.

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 short, front-loaded sentences with no filler. The action is stated first and the confirmation requirement follows immediately.

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?

With an output schema present, annotations covering safety, and full parameter documentation, the description supplies what an agent needs to act safely. It doesn't elaborate on post-return state or edge cases, but enough context is available elsewhere.

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%, so both the optional library key and required title_id are fully documented in the schema. The description doesn't add syntax or format details, which is acceptable given the schema's completeness.

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 states a specific verb and resource ('Return a loan early'), which distinguishes it from renewing or borrowing. It doesn't explicitly name siblings like renew_loan, but the 'early' qualifier gives it a distinct scope.

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?

It provides a necessary prerequisite ('Confirm with the user first'), which is useful for a destructive action. However, it doesn't say when to prefer this over renew_loan or cancel_hold, nor does it describe exclusions or alternatives.

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

Deploy Server