CGM Libre login

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

The description adds meaningful behavior beyond the annotations: it never returns the auth token, and when credentials are missing it returns mock=true with a synthetic connection. These are important behavioral disclosures that an agent cannot derive from the readOnly/idempotent hints.

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?

Three sentences, each carrying distinct value: what the tool does, when it should be used, and the two notable edge behaviors. No filler or redundant restating of the tool name.

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?

The description covers credential source, output behavior, the no-token guarantee, and the mock fallback. With no output schema, it leaves the exact normal return shape somewhat implicit, but 'list the sensors' is sufficient for an agent to call it correctly.

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 coverage is 100%, and the schema fully documents the optional privacy_mode parameter and its values. The description adds no parameter-specific meaning, so the baseline 3 applies.

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 action ('Authenticate against LibreLink Up using LIBRELINKUP_EMAIL / LIBRELINKUP_PASSWORD') and a secondary outcome ('list the sensors'). It does not explicitly name sibling alternatives like cgm_authorize_url to differentiate itself, so it stops just short of a 5.

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 gives clear usage context: it is meant as an end-to-end verification before reading glucose and can be used for demoing without credentials. It does not state exclusions or explicitly compare itself to sibling auth-related tools, but the intended when-to-use is inferable.

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