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

Annotations provide readOnlyHint=true and idempotentHint=true, so safety is already covered. The description adds meaningful context: the tool is jurisdiction-agnostic and returns total tax, effective rate, and marginal rate. This goes beyond annotations without contradicting them.

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?

Two concise sentences, front-loaded with the core purpose, no fluff. The key distinction ('no jurisdiction baked in') is stated efficiently, and the return values are listed without redundancy.

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?

Given the output schema (not shown but present), annotations covering read-only/idempotent behavior, and schema descriptions covering parameter semantics, the description completes the picture by clarifying the tool's custom-bracket model. Nothing essential is missing for an agent to invoke 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%, with clear descriptions for 'income' and 'brackets' (including the structure of bracket objects). The description reinforces the 'caller-supplied' nature but does not add syntactic detail beyond the schema, so baseline 3 is appropriate.

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?

Description clearly states the tool computes progressive tax from caller-supplied brackets, using a specific verb ('calculate' implied by 'progressive tax from') and resource ('brackets'). It distinguishes from siblings by emphasizing the brackets are caller-supplied and no jurisdiction is baked in.

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 explicitly says 'No jurisdiction, year, or rates are baked in: pass the brackets yourself,' which tells when to use this tool (custom brackets) and when not (built-in tax systems). It does not explicitly name alternatives, so it falls short of a 5.

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