LibreLink MCP Server

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

Annotations declare readOnlyHint=true, and the description aligns with this by describing a read operation ('Get information'). The description adds useful context about what information is retrieved (sensor details) and the practical purpose (checking sensor health), which goes beyond the annotation's safety profile. 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?

Two sentences with zero waste: the first states the purpose and key data points, the second provides usage guidance. It is front-loaded with essential information and appropriately sized for a simple tool.

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 read tool with annotations covering safety, the description is largely complete—it explains what data is returned and when to use it. However, without an output schema, it could more explicitly detail the return format (e.g., JSON structure), though the listed data points provide reasonable guidance.

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 0 parameters with 100% schema description coverage, so the schema fully documents the lack of inputs. The description appropriately does not discuss parameters, focusing instead on the tool's purpose and usage. Baseline is 4 for zero-parameter tools when the description is otherwise complete.

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 the specific action ('Get information') and resource ('active FreeStyle Libre sensor'), listing key data points (serial number, activation date, status). It distinguishes this tool from siblings like 'get_current_glucose' or 'get_glucose_history' by focusing on sensor metadata rather than glucose readings.

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?

Explicitly states when to use this tool: 'to check if sensor is working properly or needs replacement.' This provides clear context for usage versus alternatives like 'get_session_status' or 'validate_connection', which might check different aspects of system health.

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