MCJars

List provider versions

list_versions

Read-onlyIdempotent

Browse provider builds in catalog order (newest first). Filter by Minecraft version and channel. Each result groups all operating-system downloads for one build. Stable builds only unless requested otherwise.

Input Schema

Name	Required	Description	Default
`limit`	No
`offset`	No
`channel`	No		stable
`context`	Yes	Explain in 15-25 words, in third person, why this tool is called and how it supports the user's goal. For analytics only. You MUST describe only the abstract purpose of the tool call. NEVER include, repeat, paraphrase, or infer personal, sensitive, or identifying information from the user request or tool results, including names, emails, phone numbers, IPs, IDs, or credentials. You MUST generalize specific entities into roles such as "a user", "the customer", or "an account". Example: "Retrieving a customer's recent orders to investigate a billing issue and help support determine the appropriate resolution."
`provider`	Yes	Provider slug from list_providers, such as paper or fabric.
`llm_model`	Yes	The exact model identifier you (the assistant) are running as, taken from your system prompt or environment (e.g. "claude-opus-4-8", "gpt-5.2"). Used for analytics only. If you do not know your model identifier with certainty, pass "unknown" — never guess.
`conversation_id`	No	Pass the exact conversation_id from the server's previous response, unchanged. The server provides it on the first call — never invent one, and do not issue parallel tool calls until you have it. Keep passing the same conversation_id for the rest of the conversation, including after later user messages or on a different task; do not reset it when the user starts a new request.
`minecraftVersion`	No	Exact Minecraft game version, not the loader/build version.

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 29, 2026

TDQS

A3.7/5.0

Behavior4/5

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

Annotations already declare readOnly, idempotent, non-destructive, open-world. The description adds real value beyond that: ordering (newest first), that each result groups all OS downloads for a single build, and the stable-by-default policy. It doesn't mention pagination or rate behavior, but the safety/behavior profile is well covered.

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?

Three short sentences, each carrying distinct information (ordering, filtering, result grouping, default policy), with the core purpose front-loaded. No restatement of the title or filler.

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 no output schema, the description compensates by explaining the result shape ('groups all operating-system downloads for one build'). The analytics-only params are documented in-schema, so their absence from prose is fine; only pagination semantics are unaddressed.

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 63%, and the schema already documents provider, minecraftVersion (explicitly not the loader version), and the channel enum. The description reinforces the channel/minecraftVersion filtering and the stable default but says nothing about limit/offset pagination, which the schema leaves bare.

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?

States a specific verb and resource ('Browse provider builds') plus explicit scope: catalog order, newest first, filterable by Minecraft version and channel. An agent can distinguish it from get_download and list_providers, though it doesn't name those siblings to explain the boundary.

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?

'Stable builds only unless requested otherwise' implies the default selection behavior and when to override channel. However, it never states when to call this versus get_download or list_providers, leaving the routing decision to inference.

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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