update_expense

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

With no annotations provided, the description carries the full burden, and it does disclose the two most important behavioral traits: partial-update merge semantics ('Omitted fields are left alone') and the empty-string clearing rule for text fields. However, it is silent on how null values behave across all nullable parameters, whether an edit is reversible via undo_last, and what happens when an invalid id is supplied.

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 17-word sentence that front-loads the action ('Edit an expense') and then packs both essential behavioral rules with zero filler or redundancy. Every word 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?

An output schema exists, so return-value documentation is not needed, but for a 7-parameter partial-update tool with no annotations and 0% schema coverage, the description leaves notable gaps: null-handling semantics, behavior on an invalid id, and how this tool relates to update_last or undo_last for recovery. It covers the core merge behavior but not enough for an agent to invoke it confidently in all cases.

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 0%, so the description must compensate. It adds genuine meaning beyond the schema's bare types and defaults: that omitting a parameter leaves it untouched, and that passing an empty string clears a text field. However, it leaves non-text fields (amount, tags) ambiguous, and the schema's default of null for every optional parameter creates confusion about whether explicitly passing null clears a field or leaves it alone.

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 and resource, 'Edit an expense,' which clearly communicates a targeted mutation of one existing record. It is easily distinguished from add_expense/add_expenses (creation) and delete_expense (removal), though it does not explicitly differentiate itself from update_last, a sibling that also edits an existing expense.

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?

No guidance is given for when to select this tool over its alternatives. There is no mention of update_last (for editing the most recently added expense), add_expense, or delete_expense, and no exclusions or conditions are stated. The omission semantics ('Omitted fields are left alone') describe how to invoke parameters, not when to choose this tool.

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