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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds value beyond that: it discloses that output includes days-until, income period coverage, and a generated .ics calendar file, and clarifies no income figures are computed. It does not add anything about limits or failure behavior, but for a static read-only lookup that is minor.

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?

Front-loaded with 'Use this when...' and every sentence carries scope, output, or routing information. The single dense paragraph with an embedded parenthetical of dates is slightly heavy but not wasteful.

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?

Annotations cover safety semantics, the output schema covers return values, the input schema is fully documented, and the description covers scope, exclusions, alternatives, and what the response contains. Nothing material is missing for a static date-lookup 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?

Schema description coverage is 100%, so the baseline is 3. The description only indirectly maps to parameters ('which dates are past or next' hints at as_of_date; '.ics reminders' hints at reminder_days_before) without adding format or constraint detail beyond the schema.

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 and resource ('find quarterly estimated tax payment due dates') with concrete scope (tax year 2026, exact dates) and explicitly says what it does not do (no amounts). An agent can distinguish it from calculate_self_employment_tax and plan_quarterly_payments without opening a 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?

Gives an explicit trigger ('Use this when the user wants...'), names the alternative for the excluded case ('for amounts use plan_quarterly_payments'), and lists exclusions ('Do not use for state due dates or filing deadlines for the annual return'). When-to-use, when-not, and alternatives are all present.

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