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

With no annotations, the description carries the behavioral burden and does disclose that the tool returns ok, event or error, plus the new state. It still leaves important mutation details implicit, such as validation failure behavior, side effects, and whether the state change is atomic.

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 a single compact sentence pair with the action front-loaded, followed by valid move sources and return behavior. Every clause adds actionable information without redundancy.

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 two-parameter mutation tool with no output schema, the description covers the action, valid move source, and basic return/error shape. It is nearly complete, though it could say more about how errors are represented and what event contains.

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 description coverage is 100%, so the baseline is 3. The description adds useful meaning beyond the schema by identifying that a valid move comes from legal_moves or a move family in also_legal, which helps the agent source the move object correctly.

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 specific verb and resource: 'Apply one move' with a move object. It clearly implies this is the move-execution tool among siblings like new_game, get_state, and get_rules, though it does not explicitly name a sibling to contrast with.

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 tells the agent that the move must come from legal_moves or a move family described in also_legal, which is useful input guidance. However, it does not explicitly state when to invoke this tool versus alternatives or discuss prerequisites such as having an active session.

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