check_passability

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

With no annotations provided, the description shoulders the full disclosure burden. It declares 'Read-only' and explains the layered evaluation order, output fields, and optional direction behavior, giving the agent a complete picture of side effects and return semantics.

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?

The description is three sentences, front-loaded with the primary purpose, and each sentence adds necessary detail about procedure, output, and read-only nature. It is dense but not wasteful, though it could be slightly tighter around the return value list.

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?

Given no output schema and no annotations, the description fully compensates by listing all return values (per-direction booleans, terrain tag, stacked tile ids, optional passable), explaining the algorithm, and stating read-only behavior. There are no factual gaps for selecting/invoking the tool.

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?

Although the schema has 100% coverage with descriptions for all four parameters, the description adds meaningful context by explaining how x/y are used in the tile stack lookup, how the optional direction alters the return value, and what the mapId refers to ('Reads the map's tileset flags'). This exceeds the schema's minimal descriptions.

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 opens with a clear action ('Check whether a map cell can be walked onto') and specifies the exact scope (layered passage rule per direction). It distinguishes itself from tile-reading tools like get_tile_flags by detailing the algorithm and output.

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 provides clear context by explaining that this tool reproduces the engine's layered passage rule and reads tileset flags, implying it is the correct choice for movement/passability checks. However, it does not explicitly name alternatives or state when not to use it.

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