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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuine domain behavior beyond that: the penalty schedule that makes the received amount differ from accrued value, and the sub-twelve-month ineligibility. It does not describe the response shape or which rates/rate tables feed the calculation, which keeps it from a 5.

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?

Three sentences, front-loaded with purpose, then the two edge-case rules that most affect interpretation. Nothing is padding, and the high-stakes issue-date warning is placed where it will be read.

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 four-parameter read-only valuation with no output schema, the description covers purpose, key eligibility edge cases, and the composition of the result. The remaining gap is whether valuation uses live/current rate data or a static embedded schedule, which matters given the rated siblings in this server.

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 every parameter already carries a description, including the enum meaning and the issue-date pitfall. The description only reinforces the 'purchase date is the issue date' warning already present in the schema, adding no new syntax or default behavior. Baseline 3 applies when the schema does the heavy lifting.

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 opens with a specific verb and resource ('Value a U.S. Series I or Series EE savings bond') and even enumerates the three outputs: current worth, derivation, and net redemption amount. This clearly separates it from get_savings_bond_rates, which by name only supplies rates. It stops short of naming a sibling explicitly, so it lands at 4 rather than 5.

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?

The redemption rules (three-month interest forfeiture under five years, no redemption under twelve months) implicitly tell the agent when this tool gives a different answer than a naive rate lookup. However, there is no explicit guidance on when to choose this over get_savings_bond_rates or how to handle unsupported series such as Series HH. Usage is implied rather than stated.

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