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

Annotations already declare a safe, read-only, idempotent, closed-world read, so the bar is lower; the description still contributes real behavior: the not_covered sentinel for uncovered state/year combinations, the fact that files are tax-year specific, and an 'informational, not tax advice' disclaimer. It stops short of describing output shape or per-year coverage boundaries, which matters since no output schema exists.

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 scope and covered subtopics lead, followed by the not_covered return behavior and the disclaimer — sensible front-loading with no filler sentences. The subtopic list is dense but each item tells the agent what it will get back, so it earns its length.

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 two-parameter, fully described, read-only lookup with no output schema, the description covers scope, the topics returned, the negative-result case, and the advice disclaimer. The only remaining gap is any statement of how coverage varies by year or what to do when not_covered is returned (adjacent sibling to try).

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 coverage is 100%, so the schema already documents both parameters including the postal-code/DC/NYC conventions. The description only restates the 'one state and tax year' scoping without adding syntax or format meaning beyond the schema, so baseline 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?

Names the resource precisely (elective pass-through entity tax) and the two scoping dimensions (one state, one tax year), then enumerates the subtopics covered: eligibility, election mechanics, deadline, rate, owner credit/exclusion, estimates, sunset. That enumeration makes it distinguishable in practice from generic siblings like coverage or salt_cap, though it never explicitly contrasts itself with them.

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?

There is no statement of when to use this tool versus the sibling tools (coverage, salt_cap, bonus_conformity), and no preconditions or exclusions. The only routing hint is 'Returns not_covered when this server has no file', which describes a response case rather than usage guidance.

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