blocked_serversRetrieve Mojang's blocklist of banned Minecraft multiplayer servers as SHA-1 hashes; returns count and hashes array from the Session Server.
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
| Name | Required | Description | Default |
|---|---|---|---|
| count | Yes | Number of blocked-server SHA1 hashes returned | |
| hashes | Yes | SHA1 hashes of blocked servers |
Changes observed during successful MCP inspections.
Input schema / examplesAdded value: +[
+ {}
+]Output schema / (root)Previous value: -nullNew value: +{
+ "properties": {
+ "count": {
+ "description": "Number of blocked-server SHA1 hashes returned",
+ "type": "number"
+ },
+ "hashes": {
+ "description": "SHA1 hashes of blocked servers",
+ "items": {
+ "type": "string"
+ },
+ "type": "array"
+ }
+ },
+ "required": [
+ "count",
+ "hashes"
+ ],
+ "type": "object"
+}Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is known. The description adds valuable context beyond annotations by specifying the return structure ('count and hashes array') and the data source ('Session Server'). No contradictions with annotations.
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?
The description is a single, well-structured sentence that immediately states the verb and resource, then adds output details. Every word earns its place, with no unnecessary filler or repetition of schema data.
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 zero-parameter tool with an output schema present, the description completely covers the essential information: what is retrieved, in what format, and from where. There are no gaps in context, and the included output schema handles return value details.
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?
The tool has zero parameters, so the baseline is 4. The description does not need to explain parameter meanings. It correctly implies the operation requires no input by specifying the retrieval action.
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?
The description clearly states a specific verb ('Retrieve'), a precise resource ('Mojang's blocklist of banned Minecraft multiplayer servers'), and the output format ('SHA-1 hashes; returns count and hashes array'). It is easily distinguishable from all sibling tools, as none others deal with server blocklists.
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?
The description provides clear context for when to use this tool: when needing Mojang's blocklist of banned Minecraft servers. There are no explicit exclusions or alternative recommendations, but given the tool's unique purpose among siblings, this is sufficient. A slight deduction for not explicitly stating 'use when you need the blocklist' or naming alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.