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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds useful context beyond that: authentication is required and an absent plan yields an explicit 'no plan' response, which prevents misreading an empty result as an error.

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 the tool returns, then the parameter behavior, then the auth and empty-state caveats. No filler or redundancy.

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 single-optional-parameter read tool with no output schema, the description covers return shape, both usage modes, auth requirement and empty-state handling — everything an agent needs 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%, so the baseline is 3, but the description adds real meaning by explaining the behavioral difference between omitting 'day' (week overview) versus supplying it (full recipes with ingredients and steps) — more than the schema's format note provides.

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?

States a specific verb+resource ('user's current weekly meal plan from their EINI account') and scopes it (lunch and dinner per day, built around Swiss supermarket deals). The possessive 'My'/current framing cleanly separates it from the sibling eini_create_meal_plan without opening either schema.

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 explains the two usage modes: without 'day' returns the week overview, with 'day' returns that day's recipes with ingredients, quantities and steps. Also states a prerequisite (EINI login) and the empty-state behavior. It does not name alternatives such as eini_create_meal_plan, so it stops short of a 5.

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