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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description doesn't need to repeat safety. It adds useful context: returns one entry per currency, explains the 'unit' field and how to compute per-1 rates. This is sufficient disclosure beyond annotations.

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?

The description is concise (three sentences) and front-loaded with the main purpose. It provides necessary detail without excess. Could be slightly more structured, but overall effective.

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?

Given no parameters and no output schema, the description fully explains what the tool returns and how to interpret the fields (e.g., unit division for per-1 rate). It covers all relevant aspects for an agent to use the tool correctly.

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?

The input schema is empty (no parameters), so the description has no parameters to explain. Baseline of 4 applies as no additional semantic burden. The description focuses on output structure.

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 clearly states it returns 'all current Bank of Israel representative exchange rates vs the Israeli Shekel (ILS)' and specifies the fields (currentExchangeRate, currentChange, unit, lastUpdate). The plural name 'boi_exchange_rates' versus singular sibling 'boi_exchange_rate' distinguishes its scope as a full-list tool.

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 description says 'Use this for a snapshot of all available currencies,' which clearly indicates when to use it. However, it does not explicitly mention when not to use it (e.g., for a single currency, use the singular sibling tool). The sibling context helps, but the description could be more explicit.

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