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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description adds real value beyond them: the failure behavior ('unavailable periods are rejected'), the mode switch, and a scope disclaimer ('not financial advice').

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 dense sentences, front-loaded with the core action, then outputs, then the mode rule and caveat. No wasted words, though the output enumeration is slightly list-heavy for a single sentence.

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?

An output schema exists, so return values need not be explained, yet the description still names them helpfully. Modes, rejection behavior, and scope caveat are all present; only parameter-level detail is thin, which is the main residual gap.

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 0%, so the description must compensate. It explains the startMonth/endMonth annual-vs-monthly rule, which is meaningful given the oneOf constraint, but says nothing about amount or the start/end year semantics. Partial compensation only.

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 (convert) and resource (US dollars via BLS CPI-U) with a clear scope boundary (since 1913). It is unmistakably distinct from adjacent arithmetic siblings like compound_interest_calculator or calendar_age_difference.

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?

Tells the agent how to drive the two modes ('Omit both months for annual mode') and that unavailable periods are rejected. It gives clear operational context but never names when to prefer an alternative tool, so it falls short of full when/when-not routing.

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