Update bill

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

The description states the mutation ('Changes') which aligns with the readOnlyHint: false annotation, so no contradiction. However, it does not disclose side effects such as audit trail involvement (though the member parameter hints at it in the schema), overwriting behavior, or the availability of a dry_run preview. With annotations only indicating it's a write, the description adds minimal behavioral context beyond the obvious mutation.

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?

The description is two sentences, front-loads the core action and fields, and states the essential precondition. Every sentence carries meaning with no fluff or repetition. It is highly efficient.

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 9-parameter mutation tool with an output schema, the description only covers the core intent and precondition. It omits guidance on optional parameters (dry_run, idempotency_key, member) and their impact, and does not mention the output or return behavior beyond what the schema provides. The description is too sparse for the tool's complexity, leaving the agent to infer many usage details from the schema alone.

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 only 44%, so the description partially compensates by listing the changeable fields (name, amount, currency, due date, recurrence), which adds meaning to those parameters. However, it does not explain optional parameters like dry_run, idempotency_key, or member, and the 'bill' parameter is only described in the schema. It adds some value but doesn't fully cover the semantic gap.

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 clearly states the action ('Changes') and the resource ('a bill'), and lists the specific fields it can modify (name, amount, currency, due date, recurrence). This distinguishes it from sibling tools like add_bill (creation) and mark_bill_paid (specific status change), though it doesn't explicitly name them. The intent is clear and specific.

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 description implies when to use it: to modify the listed fields of a bill. It also states a precondition ('Needs the bill and at least one field to change'). However, it does not provide explicit exclusions or route to alternatives such as mark_bill_paid for paid status, or add_bill for new bills. The usage context is implied rather than fully explicit.

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