LibreLink MCP Server

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

The annotation 'destructiveHint: true' indicates mutation, which the description supports by stating 'Set up or update.' It adds valuable context beyond annotations by explaining security details ('stored securely using AES-256-GCM encryption with keys in your OS keychain'), enhancing trust and understanding of data handling.

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 two sentences: the first states the purpose and prerequisite, the second adds security context. Each sentence earns its place by providing essential information without redundancy, making it efficient and front-loaded.

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 mutation tool with 'destructiveHint: true' and no output schema, the description is reasonably complete. It covers purpose, prerequisites, and security, but lacks details on error handling or confirmation of success. Given the annotations and schema coverage, it's mostly adequate but could be slightly enhanced.

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?

Schema description coverage is 100%, so the schema fully documents parameters (email, password, region). The description does not add meaning beyond the schema, such as explaining parameter interactions or dependencies. Baseline 3 is appropriate as the schema carries the burden.

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 explicitly states the action ('Set up or update') and resource ('LibreLinkUp account credentials'), distinguishing it from sibling tools like 'clear_session' or 'get_current_glucose' that handle different operations. It clearly defines the tool's role in credential management.

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 explicit guidance: 'Required before using any glucose reading tools.' This tells the agent when to use this tool (as a prerequisite for other tools) and implies alternatives are not applicable for initial setup. It effectively directs usage in the workflow.

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