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

Annotations already declare this is a non-destructive, non-idempotent write with no open-world access, so the safety profile is covered. The description adds directional semantics (who owes whom) but says nothing about duplicate handling, the human-approval flow implied by approval_id, or side effects, leaving meaningful behavior undisclosed.

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 tight sentence with the trigger condition front-loaded and two short illustrative examples. The second example is arguably redundant with the first, but it clarifies both directions of the in_debt flag, so it earns its place.

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, annotations covering the safety profile, and full parameter coverage, the description only needs to establish intent — which the trigger sentence does well. The remaining gap is sibling routing and the approval_id prerequisite, neither of which is addressed.

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 100%, so the schema already documents all six parameters, including the in_debt direction flag and status values. The description's "who owes whom, the amount, and what it is for" merely mirrors amount/reason/in_debt without adding format or constraint detail, so the baseline of 3 applies.

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?

"Records who owes whom, the amount, and what it is for" gives a specific verb (records) and resource (debt) with the recorded fields spelled out. However, it never differentiates itself from debts.update, debts.list, or debts.delete, so the agent must infer that this is the creation path.

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 opening clause is an explicit trigger condition — "When the user mentions money owed" — reinforced by two concrete utterances that map naturally onto input parameters. It stops short of naming alternatives or stating when NOT to create a debt (e.g., when one already exists).

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