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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds genuine value by disclosing that the series is official and that isApproximation flags proxy-derived figures, a data-quality caveat not in annotations. It says nothing about freshness/latency or response shape beyond that, so a 3 is fair.

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-loads what the tool returns and the approximation caveat before the usage keywords. The Hebrew keyword list is slightly bulky but serves retrieval/matching purposes, so it earns its place.

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 parameters and no output schema, the description needs to convey the return content, and it does (per-track average rates, isApproximation flag, official series). It does not explain the granularity (e.g., which tracks or date coverage), which is a minor remaining 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?

The tool takes zero parameters, so the baseline is 4 by rule. The description correctly implies a parameterless global lookup rather than a per-user query.

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 resource (Bank of Israel average interest rate per mortgage track for newly issued mortgages) and scope (official series, proxy figures flagged by isApproximation). An agent can distinguish it from data-reading siblings like get_mortgage because it explicitly says no uploaded mortgage is required.

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 'Use for:' list with concrete user phrasings (ריביות בנק ישראל, הריבית הממוצעת היום, etc.) gives clear when-to-use context, and 'Needs no uploaded mortgage' implicitly excludes the account-bound tools. It does not name a specific alternative sibling, so it falls short of a 5.

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