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

Beyond the annotations (not read-only, not idempotent, not destructive), the description adds meaningful behavioral context: the caller becomes owner and members are set by name at creation, while later joining happens via group_invite. It does not detail duplicate handling or failure behavior, but the annotations and output schema cover the key safety profile.

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 short sentences, with the main purpose front-loaded and examples in parentheses. No filler or repeated schema content.

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 an output schema present and annotations covering safety, the description is sufficient for selecting and invoking the tool. It provides the essential ownership and member-joining context; only the absence of explicit guidance about existing groups and the currency meaning keeps it from a 5.

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 low (25%). The description clarifies that 'members' are the other members' names and implies 'name' is the group ledger's name, but it does not explain the required 'currency' parameter or the optional 'note'. This is partial compensation rather than full 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 starts with the specific action 'Start a group ledger' and gives concrete examples (a trip, a flat). It explicitly assigns the owner role to the caller and distinguishes this creation tool from group_invite, so the agent can tell it apart from sibling tools.

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 clearly states when to use this tool: when starting a new group ledger with the caller as owner and naming members. It also points to group_invite as the alternative for later joining, though it does not explicitly contrast with add_group_member for adding members to an existing group.

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