bpb_place_bag

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

No annotations, so the description carries the burden and largely rises to it: it discloses the empty-bag-only constraint and two named error outcomes (bag_not_empty, bags_fixed_in_item_mode). It does not disclose success return behavior, reversibility, or grid-conflict handling, keeping it out of 5 territory.

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 front-loaded sentences: action first, then precondition, then error mode. Dense and no wasted text, though the error-code clauses could be tighter.

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?

No output schema and no annotations, so the description must stand alone; it covers the main precondition and failure modes well. It falls short on success return value and coordinate semantics, which matter for a state-mutating tool but are minor against the low overall complexity.

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?

Only item_id is described in the schema (33% coverage). The description hints that x,y are a top-left grid cell but never defines the coordinate frame, whether the target cell must be free, or valid bounds, so it only partially compensates for the two undocumented parameters.

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?

Specific verb+resource: moves a backpack to a specified top-left grid cell (x,y). Clearly names its resource (backpack) which distinguishes it from bpb_place_item and from bpb_get_backpack/bpb_rotate_bag siblings. An agent can tell exactly what this does.

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?

Explicit precondition: only empty bags may be moved, with the workaround given (empty it via bpb_place_item/bpb_store_item first) and the error path (bag_not_empty). It also flags the item-mode block (bags_fixed_in_item_mode). Missing explicit when-to-use vs rotate_bag or open_edit, but the core routing conditions are present.

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