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), and the description adds genuinely new context: the results are projections, not authoritative determinations ('Estimates only'), and the math matches a named external calculator, which signals reproducibility. It does not cover input-validation failures or edge cases such as what happens with unsupported loan types.

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?

Purpose is front-loaded in the first clause, and the output enumeration is dense but each item is distinct and useful. The trailing two sentences ('Same math as...', 'Estimates only.') are short and earn their place as provenance and disclaimer.

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 14-parameter tool with no output schema, listing the returned figures (first payment, total paid, payoff years, forgiveness, cheapest plan, PSLF) is exactly the missing information an agent needs. What remains unstated is minor: nothing about computation cost, whether any plan can be omitted from results, or how private loans are treated in the comparison.

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% and already explains every enum, default and bound, so the baseline is 3. The description's references to loan dates gating plan availability and PSLF timing for government/501(c)(3) workers restate what the schema's employer and loan_dates descriptions already say, adding little beyond it.

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 ('Estimates each federal repayment plan') and enumerates the exact outputs it computes, so an agent knows precisely what it gets back. Siblings (get_plan_rules, compare_refinance_offer) are not named or contrasted, so differentiation is left to inference.

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?

No explicit when-to-use, when-not-to-use, or alternative routing. Nothing tells the agent to prefer get_plan_rules for authoritative plan rules or compare_refinance_offer for private refinancing, so the boundary between the three tools must be guessed from names alone.

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