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

Annotations already declare this is a non-read-only but non-destructive write, and the description adds real context beyond them: board_ids must be the complete ordering, and the stack's display_url always mirrors the active board. However, for an upsert tool it leaves a critical behavior unstated — whether omitted fields (name, board_ids) are preserved or cleared on update, and what permissions are required.

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?

Four tight sentences with zero filler; the core behavior is front-loaded and the create/update rule and display_url note each follow in one clause. Nothing is repeated from the title or schema.

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 3-parameter upsert with no output schema and no annotations explaining semantics, the description covers ordering, creation, and display behavior but omits the preserve-vs-replace question for partial updates. An agent could invoke it but might unintentionally wipe a stack's board ordering or name.

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 33%, so the description must compensate, and it largely does: stack_id is defined by its absence semantics (new stack) and board_ids by its 'complete ordering' contract. Only 'name' relies on the schema example alone, which is adequate for a trivial field.

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 gives a concrete verb and resource ('Fasst Bildschirme zu einem Stapel zusammen') and even explains the domain concept via analogy ('wie mehrere Desktops') plus an example ('ein Stapel pro Unterrichtsstunde'). The create-vs-update behavior ('Ohne stack_id wird ein neuer Stapel angelegt') clarifies the somewhat generic 'save' verb. It does not explicitly distinguish itself from board siblings (create_board, update_board, show_board), so it stops 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?

It gives a clear usage context (one stack per lesson) and an explicit condition that selects create versus update (absence of stack_id). There is no statement of when not to use it or which sibling to prefer for board-level operations, so it is clear but not exhaustive.

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