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

Annotations indicate readOnlyHint=true, and the description confirms read-only behavior by describing computation and estimation. It adds valuable behavioral details beyond annotations: annualizing income, calculating safe-harbor targets, providing per-quarter amounts and due dates, and handling California's unique installment schedule. No contradictions with annotations.

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 extremely concise: two sentences that front-load the usage scenario and then list the key outputs. Every clause adds essential information (federal taxes, safe harbor, quarterly amounts, due dates, California timing). No wasted words or repetition.

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 complexity of quarterly tax estimation, the description covers major outputs: federal taxes, safe harbor, quarterly amounts, and due dates. It also notes California's specific timing. The output schema is present, so return values need not be described. However, it omits explicit mention that for non-California states only federal figures are provided, though this is implied in the state parameter description. Overall, quite complete.

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. The description adds contextual meaning beyond the schema by explaining how parameters tie to real-world concepts like annualized income and safe-harbor targets. For example, it mentions California installment timing, which relates to the state parameter. While schema adequately describes each parameter, the description enriches understanding of their combined use.

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 explicitly states the tool's purpose: 'Use this when a freelancer or business owner asks how much estimated tax to pay or whether they are underpaid for the year.' It lists specific computations (federal self-employment and income tax, safe-harbor target, per-quarter amounts, due dates, California installment timing), clearly distinguishing it from siblings like estimate_irs_penalty or estimate_rental_income.

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 opens with a clear usage scenario: 'Use this when a freelancer or business owner asks how much estimated tax to pay or whether they are underpaid.' It does not explicitly list when not to use or name alternative tools, but the context of sibling tools provides implicit differentiation. A score of 4 reflects clear guidance without exclusions.

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