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

Annotations already declare read-only, idempotent, non-destructive behavior, so the safety profile is covered. The description adds meaningful domain context beyond that: the 2026 tax year and the assumption of progressive brackets plus standard deduction, which tells the agent what model is being applied. It does not flag limitations such as itemized deductions being excluded, which keeps it short of a 5.

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 sentences, front-loaded with the core purpose and method before the routing hint. The inline return-field listing is somewhat redundant given an output schema exists, which is the only minor inefficiency.

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 low-complexity, two-parameter financial calculator with full schema coverage, an output schema, and complete annotations, the description covers method, tax year, and a cross-reference. It is essentially complete, though noting that standard-deduction-only assumptions are baked in would tighten it further.

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 both the income and filing_status parameters are already documented with the enum values and default. The description adds no further parameter-level detail (e.g., whether income is gross vs. net, currency, or unit expectations), so the baseline of 3 applies.

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 (calculate), resource (US federal income tax), tax year (2026), and methodology (progressive brackets with standard deduction). This distinguishes it from the many neighboring tax calculators such as calculate_us_state_tax, calculate_us_paycheck, and calculate_canada_federal_tax.

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?

It points to list_bundles for related 'finance-us' calculators, which gives some routing context, but it never states when to use this tool versus close alternatives like calculate_us_state_tax or calculate_us_paycheck. Usage is implied rather than explicitly scoped.

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