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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description still adds real value by disclosing the modeled rules (tiered 3/4/5-year exclusions, $15M cap, post-July 4 2025 acquisition split) and the qualifying-stock assumption, though it says nothing about the output or precision of the estimate.

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 tight sentences plus a link, with the core purpose and rule vintage front-loaded and the caveat immediately after. Nothing is wasted and nothing is buried.

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 should say what comes back (exclusion amount, tier applied, taxable remainder), but it does not. The modeling scope and assumption are well covered, so it is adequate but leaves the agent guessing at the return shape.

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 all five parameters are already documented, making 3 the baseline. The description adds only indirect meaning — the July 4 2025 acquisition cutoff and the $15M lifetime cap hint at how acquired_date and prior_gain_usd interact — but gives no explicit parameter guidance.

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 (estimates) and a precisely scoped resource (US federal capital gains exclusion for QSBS under IRC Section 1202), plus the rule vintage it models. An agent can tell this apart from siblings like tax_deadlines or startup_valuation without opening the schema.

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 clause 'Assumes the stock otherwise qualifies' sets an important precondition, implying this is a computation tool rather than a qualification checker. However, no alternative tool is named and there is no explicit when-not guidance, so routing is only implied.

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