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

Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is known. The description adds real substance beyond that: the source stack ceases to exist, pages are relocated, and page placement semantics ('a home stays a home') are preserved. It stops short of stating permissions required or irreversibility explicitly.

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?

A single dense sentence front-loads the action and direction before the consequences and precondition. No filler; every clause carries information about behavior or invocation policy.

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 annotations already covering safety, the description supplies the irreversibility consequence, relocation semantics, and a usage precondition — enough to call it correctly. A note on permissions or the response (e.g., what the merged stack looks like) would close the remaining gap.

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 `from`/`into`/`team` descriptions are already clear. The description's 'every page in `from` moves to `into`' restates rather than extends the schema's 'stack that goes away' / 'stack that keeps everything', and the optional `team` scoping parameter is not addressed. Baseline 3 is 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?

States a specific verb+resource ('Fold one stack into another') and immediately defines the mechanics: pages in `from` move to `into`, and `from` is gone. This distinguishes it from siblings like update_stack, copy_space, delete_stack, and file_in_stack without needing to open a 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?

The closing clause, 'Only when the person asks,' is an explicit gating condition that tells the agent not to invoke this proactively — valuable for a destructive merge. It does not name alternative sibling tools or spell out when a rename/copy is preferable, so it falls short of full when/when-not/alternatives guidance.

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