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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower, yet the description still adds real behavior: results are downsampled to at most 1500 points, values arrive in the account's unit, and older periods take a heavier 'full query' path. It stops short of explaining the reduction method or ordering, so it is not fully transparent.

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 tight sentences with no filler, and the default period is stated up front where an agent will see it first. The phrase 'full query' is internal jargon that leaks implementation detail rather than clarifying behavior.

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?

With no output schema and only two optional parameters, the description covers the essentials an agent needs: default window, unit, point cap, and id presence for manual entries. What is missing (ordering, aggregation when capped, or why older periods are costlier) is relatively minor for a read-only tool.

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 already documents that from/to accept local dates or ISO date-times. The description adds the default range (last 24 h) and the account unit, which the schema does not state, but says nothing about range inclusivity or how the two bounds interact, so it is only marginally beyond the baseline.

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?

Names the specific resource (glucose readings) and its scope (a period, default last 24 h), plus the account's unit and a 1500-point ceiling. It reads clearly as a read/fetch tool distinct from the log_* siblings, but it never explicitly contrasts itself with alternatives such as get_stats or get_entries.

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?

Gives useful calling context: no arguments means the last 24 hours, manually logged readings carry an id, and older periods trigger a 'full query'. However, it never states when an agent should prefer this over get_stats/get_entries or what constraints make a request inadvisable, so guidance is implied rather than explicit.

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