finn-seller-mcp

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check_duplicate

Verify whether an item is already listed locally or on finn.no before preparing a new ad, using perceptual photo hashes and title matching.

Instructions

Check whether an item was already listed (locally or on the user's finn.no account).

    Call this BEFORE preparing a new ad. Local photos are matched by
    perceptual hash; finn.no ads (any state: active, sold, expired, draft)
    are matched by title.

Input Schema

Name	Required	Description	Default
`title`	Yes
`photo_paths`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.2.0Oct 25, 2026

TDQS

A4.4/5.0

Behavior4/5

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

With no annotations, the description carries the burden and does well: it discloses that photos are compared by perceptual hash and titles against finn.no ads in any state (active, sold, expired, draft) — non-obvious behavior that materially affects interpretation of results. It omits any statement about permissions, rate limits, or the cost of the scan, and defers match/return semantics to the output schema.

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 sentences, front-loaded with the purpose, then the when-to-use rule, then the matching mechanics. No filler or restatement of the tool name.

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 two-parameter read-only check with an output schema available, the description covers what is compared and against what sources, which is the information an agent needs to call it correctly. Only the optionality of photo_paths and the distinction from confirm_not_duplicate are left implicit.

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 0%, so the description must compensate, and it does partially: it explains that photo_paths feed perceptual-hash matching and that title is the matching key for finn.no. It does not state that photo_paths is optional or what happens when it is omitted, nor the expected path format.

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?

States a specific verb and resource (check whether an item was already listed) and scopes it to two distinct backends: local records and the user's finn.no account. It also distinguishes the matching mechanism per backend, so an agent understands exactly what 'duplicate' means here.

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?

"Call this BEFORE preparing a new ad" gives an explicit trigger point in the workflow, which is stronger than most sibling definitions. It does not name or contrast with the obvious sibling confirm_not_duplicate, leaving the agent to infer the distinction between detection and confirmation.

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