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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds real behavioral context beyond that: a hard 100-entry cap per call, the units (EUR cents), the 'own machine only' scope, and the pagination trigger, though it says little about the shape of the returned balance/limits object.

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 sentences, each carrying distinct information: what is returned, the pagination mechanics, and the sibling routing. The key scope and cap are front-loaded with no filler.

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 zero-required-param read with full schema coverage and annotations covering safety, the description supplies everything an agent needs: scope, units, cap, pagination procedure, and the alternatives for the two mutating operations.

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 100% and the single offset parameter is documented in the schema, so baseline would be 3. The description earns an extra point by supplying concrete paging mechanics (offset=100, 200, ...) and tying offset to next_offset, which the schema only gestures at.

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 (read) plus concrete resources (EUR-cent balance, spending limits, latest ledger entries) scoped to the authenticated sandbox machine's own wallet. It is immediately distinguishable from the two wallet-related siblings it names.

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?

Explicitly routes the agent: fund_wallet for creating a test funding checkout, set_wallet_limits for changing limits, and states this tool does neither. It also gives the condition for paginating (when next_offset is present).

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