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

Annotations already declare readOnly, idempotent, closed-world and non-destructive, so the safety profile is handled. The description adds two things annotations cannot: results are ordered newest first, and a read failure surfaces as a named source_unavailable error rather than a misleading empty list — valuable for an agent deciding whether an empty result means 'no data' or 'something broke'.

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 what is returned, then how to call it, then the failure mode and the scope disclaimer. No filler, and each sentence carries distinct information.

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 supplies the return shape itself (field list plus ordering), and it covers the error contract. For a zero-required-parameter read tool, nothing an agent needs to call it correctly is missing.

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 baseline is 3 regardless. The description goes beyond the schema by explaining the mode semantics — slug absent means list, slug present means single episode, series filters the list — which the schema only hints at with 'Optional episode slug, from the list'. The limit parameter's paging role is left entirely to the schema.

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?

Names a specific resource (FRU News episodes published by FreeRateUpdate) and enumerates what each episode carries: slug, title, description, series, publication date, page URL. The closing line — 'editorial content, not a rate, an offer or an approval' — explicitly separates it from the rate/lender/state siblings in the same toolset.

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 explicit branching instructions: omit slug to list, pass slug to fetch one episode, pass series to narrow the list. That covers all three call patterns an agent could attempt, with no ambiguity about which parameter combination produces which mode.

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