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

Beyond the read-only, idempotent, non-destructive annotations, the description discloses precisely what the calculation includes: the Publication 915 Social Security worksheet, 65-plus standard deduction additions and phase-out, ordinary brackets, the 0/15/20% capital gains stack, the 3.8% NIIT, bracket room, and the IRMAA tier two years later. This gives an agent an unusually complete picture of the tool's behavior.

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 description is a single dense sentence that conveys a large amount of output detail without fluff, and the final 'Federal only' is a useful scope marker. A colon-list structure keeps it readable, though an explicit leading verb such as 'Calculates' would make it even more immediate.

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?

With no output schema, the description is the sole signal for what the tool returns, and it does enumerate the major output blocks: taxable Social Security, deduction, ordinary brackets, capital gains stack, NIIT, bracket room, and IRMAA. It could add caveats about assumptions or default behavior with zero inputs, but it is largely complete for a federal tax estimate tool.

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?

The input schema already documents all six parameters with 100% coverage, so the baseline is 3. The description adds contextual connections such as the 65-plus additions relating to ages and the 0/15/20% stack relating to capital gains, but it does not add meaning beyond what the parameter descriptions already provide.

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 identifies the resource — a retiree's federal income tax for tax year 2026 — and enumerates the exact computed components, making the tool's purpose unmistakable. It stops short of using a literal verb like 'calculates' or 'estimates', and differentiation from siblings rests mostly on the 'Federal only' tag.

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 clearly scopes the tool to federal income tax for retirees, and the closing 'Federal only' tells an agent it is not for state tax questions, which siblings like state_retirement_taxes would cover. It does not explicitly name sibling tools or provide richer when-to-use versus when-not-to-use guidance, but the context is clear.

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