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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=false, and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful behavior context — names must be unique per kind — which explains the non-idempotent nature and an expected failure mode. It still omits what happens on a duplicate name, permission requirements, or defaults applied to omitted color/icon.

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 purpose is correctly front-loaded, but roughly half the text is boilerplate about amounts in minor units and date/month formats that are irrelevant to create_category's schema. That content earns no place here and dilutes the useful uniqueness note.

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 four-parameter creation tool with no output schema, the description should at minimum cover the required fields, the optional enum fields, defaults, and duplicate-name behavior. Instead it covers the required fields only partially and spends its remaining budget on amount/date conventions that belong to add_transaction or set_budget.

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% for four parameters, so the description must carry the load. It clarifies only two: that kind is expense-or-income and that name is unique per kind. It says nothing about icon or color (the latter having a 16-value enum), and the amount/date sentences describe parameters that do not exist on this tool, actively adding noise.

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 opening clause states a specific verb and resource ('Create an expense or income category') and adds the uniqueness constraint per kind, so the agent knows exactly what object is produced. It does not explicitly contrast itself with create_account/create_goal or with update_category, so it falls short of full sibling differentiation.

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?

There is no guidance on when to create a new category versus reusing one via list_categories or renaming via update_category, and no mention that name and kind are required while icon/color are optional. Usage is only implicitly derivable from the verb.

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