Check out

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

Annotations already declare readOnlyHint=false and destructiveHint=false, so safety is covered. The description adds genuine behavioral detail with 'first free seat is used' for licenses, but says nothing about failure modes (item already checked out, no free seat) or permission requirements.

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?

One verb sentence followed by a dense, scannable mapping expression. Zero filler and the operation is front-loaded before the constraint matrix.

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 9-parameter mutation with no output schema and thin annotations, the description covers the highest-risk ambiguity (which target type each resource accepts). It omits error behavior and quantity semantics for consumables, which an agent may still need.

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 67%, so the schema carries most of the load, but the description adds meaning the schema does not: the resource->target matrix clarifies the relationship between 'resource', 'to' and 'target_id', and 'first free seat' explains license behavior. It leaves 'name', 'note', 'quantity' and 'expected_checkin' entirely to the schema.

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 and resource ('Check an item out') and immediately disambiguates it from the checkin sibling by naming the operation's direction. The resource->target matrix makes clear exactly which combinations this tool handles.

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 matrix effectively encodes when each resource/target combination is valid, which is real usage guidance an agent would otherwise have to guess. It stops short of naming alternatives or exclusions (e.g., use checkin to reverse, or what to do if a license has no free seat).

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