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

The annotations already state readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds real behavioral detail the annotations don't: the exact combination formula, the 0.01 percent rounding rule, and the zero floor (which implies negative inflation inputs are handled). It doesn't state the output unit or magnitude range explicitly beyond the rounding clause.

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 with the formula front-loaded and the rounding/floor constraints attached to it. The trailing "Use it for rate predictions" is the weakest clause but costs little.

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 carries the return-value burden and does so by specifying the rounding precision and zero floor. Both required parameters are covered and the tool is a transparent pure function, so an agent has enough to call it correctly; only the explicit output unit (percent vs. decimal) is left to inference.

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 baseline would be 3, but the description goes beyond the schema by showing how the two inputs interact (fixed + 2×inflation + fixed×inflation), which is the cross-term semantics the per-parameter schema text omits. It also signals that the inflation input can be negative via the floor, matching the schema's -10 minimum.

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 names a specific computation (Treasury composite rate formula) and spells out the exact formula, which clearly separates it from the sibling getters (get_current_i_bond_rate, get_i_bond_rate_history) and the estimator. It stops short of explicitly naming which sibling to use instead, so it is clear but not fully differentiated.

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?

"Use it for rate predictions" gives only a loose context cue and does not say when to prefer this over get_current_i_bond_rate or estimate_i_bond_value, nor any prerequisites. Usage is implied rather than specified.

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