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

Annotations already cover read-only/non-destructive safety, but the description goes further: it discloses per-row observation timestamps, source and staleness status, that personalization is transparent and 'nothing is fabricated', and the refusal policy for advice requests. This is rich behavioral context beyond structured fields.

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 the core resource and scope, then personalization, then constraints. Dense and mostly waste-free, though the advice-refusal sentence and provenance guidance are somewhat beyond what an invocation needs.

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-shape burden and does so reasonably (rows carry observation timestamp, source, staleness; provenance block can be omitted). Coverage of what comes back is adequate, though it does not describe ordering or pagination behavior beyond max_results.

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 all five parameters are already documented in detail; the description mostly restates balance/tier resolution and provenance toggling. It adds only marginal meaning (e.g., 'nothing is fabricated'), so the baseline 3 is appropriate.

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+resource up front ('Current savings APYs: FDIC national average plus rates RateZip observed'), and the product scope distinguishes it from siblings like get_cd_rates and get_mortgage_rates. An agent can identify the tool's output without opening the 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 clear when-to-use context (personalization via balance/state/credit_score) and explicit when-not behavior (decline financial advice, never recommend a provider or claim account-opening). It does not explicitly route to alternatives such as compare_deposit_options or calculate_deposit_earnings_difference, so it stops short of 5.

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