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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine value beyond them by disclosing the return contents (formulas, dates, limits, statutory/regulatory citation, page link) and the source of truth, which lets an agent judge whether the output is authoritative enough to cite. It stops short of noting staleness or that the rules are snapshot/point-in-time reference data.

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 sentences, front-loaded with the purpose and followed by the return shape and the optional-parameter behavior. The enumeration of eight plan topics is somewhat listy but maps directly to the enum values and is therefore informative rather than filler.

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 one optional parameter, no output schema, and full annotation coverage, the description does the needed work: it explains what comes back and where the rules originate. The only gap is a lack of any statement about data freshness or effective dates for time-sensitive items like SAVE's end and the 2026 poverty guidelines, which an agent citing these rules would want to know.

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% and the single enum parameter is fully documented with all eight allowed values, so the schema carries the semantics and the baseline of 3 applies. The description adds only a marginal note about omitting the topic. That note also diverges slightly from the schema, which says omitting returns 'a one-line summary of each' while the description says 'the list of topics,' a small ambiguity about what the no-argument call actually yields.

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 states a specific verb and resource: it returns the published rules (formulas, dates, limits) behind each named federal repayment plan, plus the statute/regulation and a page link. It enumerates the covered topics, which concretely bounds the scope. Sibling differentiation is only implicit — it is clearly the reference-lookup tool rather than compare_repayment_plans or compare_refinance_offer, but no sibling is named.

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?

Usage context is implied by the source framing ('as studentloan.help states them') and by the 'Omit topic for the list of topics' line, which tells the agent how to start exploring. There is no explicit when-to-use vs. when-not statement and no mention of the comparison siblings, so an agent must infer that this is for looking up rules, not for evaluating a borrower's options.

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