Who owes what

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

Annotations already provide readOnlyHint=true and idempotentHint=true, so the description doesn't need to repeat that. It adds valuable context about the output scope (net positions and a minimal settlement plan), which goes beyond the annotations. No contradictions.

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?

A single, well-structured sentence that front-loads the core action ('Report every member's net position') and then adds a concise qualifier about the settlement plan. No wasted words.

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 parameters, read-only/idempotent annotations, and an output schema present, the description sufficiently covers what the agent needs to invoke it correctly. The return format is likely covered by the output schema, so no additional explanation is needed.

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 has zero parameters, so the baseline of 4 applies. The description doesn't need to explain any parameters, and the schema confirms an empty argument list.

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 states a specific verb ('Report') and a clear resource ('every member's net position and the fewest payments that settle it'). It clearly distinguishes from siblings like 'what_do_i_owe', which likely targets an individual, whereas this covers all members.

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 phrase 'every member' implies a group-wide report, giving some context for when to use it. However, it does not explicitly state when to prefer this over alternatives like 'what_do_i_owe' for individual balances, nor does it mention any exclusions.

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