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

Beyond readOnlyHint/destructiveHint/openWorldHint, it discloses the free-plan retention limit (last 7 days), which constrains what results are even obtainable, and it flags that food names and notes are untrusted data that must not be treated as instructions. Both are behavioral facts an agent cannot get from the annotations or schema.

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, front-loaded with what is returned, then when to call it, then the caveats. No sentence restates the title or the annotations, and each contributes information the agent would otherwise lack.

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 one optional parameter, no output schema, and a read-only annotation profile, the description supplies the missing pieces itself: return contents, plan-based retention, and an injection caution. An agent can call this correctly from the description plus schema alone.

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 single date parameter is fully documented in the schema, including the YYYY-MM-DD format, the user's time zone, and the today default. The description adds nothing to that parameter, leaving the high-coverage schema baseline of 3 appropriate.

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 names the resource (one day's logged meals) and enumerates exactly what comes back: per-meal net carbs and rating, day total, daily target, and net carbs remaining. That field-level clarity distinguishes it from get_week, which aggregates over a longer span, without either schema being opened.

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?

It gives concrete triggering contexts ('how am I doing today?', before suggesting a meal), which is explicit when-to-use guidance. It stops short of naming an alternative such as get_week for trend questions or estimate_meal for hypothetical intakes, so no exclusion is stated.

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