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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is known. The description adds valuable behavior beyond that: mid-period weekly/monthly summaries cover period-to-date (Monday–today example), the isPartialPeriod field explains which case applies, and the JSON-not-CSV note clarifies the response shape. This is exactly the kind of nuance an agent needs to interpret results correctly.

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 with zero filler. The first sentence front-loads the purpose and contents, the second clarifies a subtle time-window behavior, and the third preempts a format misconception. Every sentence 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?

For a read-only aggregation tool with full schema coverage and clear annotations, the description covers the what (contents), when (daily/weekly/monthly), edge cases (mid-period), and response format (JSON). No output schema exists, but the description compensates by naming the key field (isPartialPeriod). Nothing essential 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 description coverage is 100%, and the schema already explains the date reference semantics, limit default/max, and period enum. The description adds no new parameter-level meaning; it is consistent with the schema but does not go beyond it. Baseline 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 states the verb 'Get' and the resource 'market-wide overview', and enumerates specific contents (top gainers/losers, volume/turnover/crossings, ASI/S&P SL20, sectors). This clearly distinguishes it from sibling tools like get_index_data (single index) or screen_stocks (screening), which an agent could otherwise confuse it with.

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 gives clear context: this is the market-wide snapshot tool, not a per-symbol or per-index tool. However, it does not explicitly say 'use this when X, not when Y' or name alternative tools. The 'not CSV' note addresses format, not usage, so a small gap remains.

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