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

Annotations already indicate destructiveHint=true, readOnlyHint=false, and idempotentHint=false, so the tool's mutating nature is disclosed. The description adds the demo-disabled context and that it operates on the authenticated business, but does not describe specific side effects or requirements beyond the annotations.

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 very concise and front-loaded with the core action. Every word serves a purpose, though the Spanish demo note might be slightly opaque to some agents. Overall it is appropriately sized.

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 the simple 3-parameter schema and existing annotations, the description is minimally adequate but lacks contextual completeness for a destructive action. It does not mention what happens after closing, whether opening/closing requires specific conditions, or return behavior. However, the schema and destructiveHint fill some gaps.

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 all parameters (action, monto, nota) are already documented with clear descriptions. The tool description itself adds no additional parameter semantics beyond what the schema provides, which matches the baseline for high schema coverage.

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 uses a specific verb ('Opens or closes') and a clear resource ('cash register shift') for the authenticated business. This clearly distinguishes it from sibling tools like caja_consultar_saldo (balance) and open_caja_status (status).

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 description provides no guidance on when to use this tool versus alternatives or when to open vs close a shift. The demo-disabled note is a constraint but not usage guidance. No exclusions or prerequisites are mentioned.

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