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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered. The description adds value beyond that: it discloses partial-update semantics (only passed fields change) and, importantly, that switching type moves all of the category's records between income and expense — a significant side effect the annotations cannot convey.

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?

One sentence covering the field set and partial-update behavior, followed by one sentence on the type-change side effect. Front-loaded, no filler, every clause 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?

For a mutation tool with a full output schema, safety annotations already present, and 100% schema coverage, the description supplies the missing pieces (partial update, cross-record consequence). An agent has everything needed to call it correctly.

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 baseline is 3, but the description adds the non-obvious semantics that omitted fields are left unchanged and ties the type field to a cross-record side effect. It goes beyond restating the schema's per-field docs.

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?

States a specific verb (changes) and resource (category) and enumerates exactly which fields it touches (name, type, description, color). The resource name cleanly separates it from update_record, update_payment_method, and update_recurring_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?

Usage is implied by the name and the create/list/delete siblings, and the partial-update note tells the agent it can pass a subset. However, there is no explicit when-to-use-vs-alternative guidance and no stated prerequisites or exclusions.

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