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

Annotations already establish read-only/idempotent behavior. The description adds valuable behavioral context beyond that: comparison basis (share count not value), security merging (ticker/CUSIP), filing delay (45 days after quarter end), and the grouping/ordering of individual moves. No contradictions with annotations.

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?

The description is longer than average but every sentence contributes: it covers purpose, both modes, comparison rules, data source, and timing. The front-loaded purpose sentence orients the agent immediately, and the subsequent detail is organized logically. Slightly dense but not wasteful.

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, idempotent data retrieval tool with a full output schema and 100% parameter coverage, the description covers all agent-relevant details: default behavior, variant behavior, data merging, comparison criteria, and data freshness. Nothing essential is missing for correct invocation.

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 parameters are already documented. The description adds extra meaning: it explains what changes when superinvestor_cik is provided (grouped by action, largest positions first, shares_change_pct in percent) and clarifies that quarter defaults to the latest comparable quarter. This exceeds the schema explanations.

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 a specific verb and resource: 'what the curated superinvestors bought and sold in one quarter according to 13F'. It also distinguishes from siblings like get_insider_trades (insider trades, not 13F) and get_stock_13f_holders (single stock holders, not quarterly changes). The two modes (with/without superinvestor_cik) are clearly laid out.

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 explains when to use each mode (default summary vs. individual moves with superinvestor_cik) and caveats like 'only superinvestors that filed both quarters are compared'. It does not explicitly name sibling tools to avoid, but the context is clear enough for an agent to select this over other 13F-related tools.

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