List groups

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: it discloses that member names accompany each group and, critically, the sign convention for balances (positive = group owes user, negative = user owes group). It omits nothing major for a zero-argument read, though it does not say whether all groups are always returned.

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?

Two sentences, zero waste. The resource and returned fields come first, and the balance-sign interpretation follows because it is the one detail an agent could otherwise misread. No restatement of the name or title.

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?

With no input schema and no output schema, the description carries the burden of explaining the return shape, and it does so at a useful level: groups, member names, per-user balance, and sign semantics. Only minor gaps remain, such as ordering or whether an empty list is possible.

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?

The tool takes no parameters, so the baseline is 4; there is no parameter semantics to compensate for. The description correctly spends no words on inputs and instead explains output meaning.

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 ("Lists the user's Splitwise groups") and enumerates the returned content: member names and the user's balance in each group. This implicitly separates it from the singular get_group sibling, though no sibling is named explicitly.

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?

Usage is only implied: an agent can infer this is the entry point for enumerating groups before calling get_group or list_expenses. There is no explicit when-to-use, when-not, or pointer to alternatives such as get_balances for aggregate totals.

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