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

Annotations already declare this is a safe, non-destructive, non-open-world read. The description adds genuinely useful context beyond them: the data derivation (three years of daily closes), the exact metrics computed (1d/1m/3m/YTD/1y changes plus 52-week range), and the update cadence ('Daily after the US close'). It does not cover error behavior or result limits, but for a read tool with annotations this is solid.

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 its scope, then a compact list of returned metrics, then the URL mirror and cadence. The opening sentence is dense with examples, but every element (scope, fields, source, freshness) earns its place; no filler sentences.

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 by listing the level, multi-horizon changes and 52-week range. It also documents data provenance and staleness, which matters for a market data tool. Only the lack of sibling differentiation and result-size/error notes keeps it below complete.

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 100% and the single parameter is fully documented there (vendor symbol or label fragment, with examples, and the omit-to-list behavior). The description restates the board context but adds no new syntax or matching rules beyond what the schema already provides, so the baseline of 3 applies.

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 names a specific resource (Closelooknet's market board instruments) and enumerates exactly what is covered (indices, FX, crypto, futures proxies, US funds) with concrete examples. It also states the fields returned. It stops short of distinguishing itself from lookalike siblings such as get_index_snapshot or get_price_history, so it is clear but not fully disambiguated.

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?

Usage is implied rather than stated: the description explains that omitting the symbol lists the whole board and that data refreshes daily after the US close, which tells an agent how the tool behaves. However, there is no explicit when-to-use versus siblings like get_index_snapshot or compare_indices, and no exclusions.

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