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

Adds behavior beyond the annotations: the child only sees the message on the next open, and empty text without a sticker removes the existing feedback. That last point is a removal side effect that sits in tension with destructiveHint=false, but the description is the honest source here. What it doesn't state is whether a send is visible/editable afterwards or what happens on invalid package_id.

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 dense sentences ordered by importance: what it does, how to write it, and the edge case that deletes feedback. No filler and nothing buried at the end.

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 4-parameter mutation tool with annotations and no output schema, this covers scope, tone expectations, visibility to the child, and the destructive edge case. The remaining gap is the sticker parameter and any permission prerequisite (e.g., whether the teacher must review first as a hard rule or just a recommendation).

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 only 25%, so the description has to carry weight: it explains the item_id/package_id scope split and gives real semantics for text (empty text = removal). However, the sticker parameter's purpose and effect are only obliquely implied ('ohne Sticker'), and package_id is left entirely to the parameter name.

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 and resource ('Schreibt dem Kind eine Rückmeldung') and explicitly distinguishes the two scopes: a single Baustein via item_id versus the whole Lernpaket. It does not differentiate itself from nearby siblings such as speak_support_item or add_support_item, so an agent still has to infer which of the feedback-related tools to pick.

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 clear usage context: when to target an item vs the whole package, how the text should read ('Kurz, freundlich, konkret und passend zur Klassenstufe'), and the workflow rule to show it to the teacher first. What is missing is an explicit pointer to an alternative tool when, for example, the feedback should be spoken or is a system-generated item.

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