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

Annotations already declare readOnlyHint=true / destructiveHint=false, so safety needs no restating; the description instead adds real behavioral context: data can be decades long, output is summary statistics (latest, 1M/3M/1Y/5Y change, range, percentile position) plus resampled points. It does not cover failure modes (e.g., unknown code, conflicting address modes) or date defaults, keeping it below 5.

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 resource and scope, then addressing modes, then return shape, then use cases — a sensible order with no filler sentences. The long comma-separated series enumeration is informative but dense; it slightly crowds the paragraph.

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-value burden and does so (summary stats + resampled points). Combined with a fully documented 8-parameter schema, an agent has enough to call it correctly; only edge-case behavior (default date window, conflicting address params, unknown series) is left unspecified.

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 3 is the floor; the description earns above that by explaining the three mutually alternative addressing modes (code vs. instrument vs. indicator+country) and by pointing to the sibling tools whose historyCode values the `code` param accepts. It does not disambiguate precedence if more than one address mode is supplied.

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?

Opens with a concrete verb+resource ('Historical time series behind the Global Markets dashboard') and enumerates the exact data families covered (policy rates, 10Y yields, FX, commodities, VIX, DXY, 2s10s, per-country macro). It is clearly separable from siblings like get_global_markets_overview and get_macro_indicators, which it names as upstream code sources.

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 three concrete routing rules for addressing a series (historyCode from a named sibling, instrument name, or indicator+country) plus example questions ('how have rates moved since 2022', 'plot Brent over 10 years'). It stops short of explicit when-not-to-use/exclusion guidance versus the snapshot-style siblings, so it lands at a strong 4 rather than 5.

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