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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely new context beyond that: the data source is Yahoo Finance via yfinance and no API key is required. It does not disclose result ordering or ranking behavior, which would be the next useful detail.

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?

Purpose and return value are front-loaded in the first two sentences, and the when-to-use list is scannable. The asset_type option list is wasted space since the schema already enumerates the same values, keeping it short of a 5.

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 an output schema present and read-only annotations, the description does not need to explain returns, and it still summarizes them as symbols with exchange and asset type. The one gap is that the schema exposes several unrelated infrastructure/wholesaler parameters that the description never addresses, leaving an agent to guess whether they matter for a simple ticker lookup.

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?

The nested schema documents query, asset_type, max_results and the infra fields in detail, so the schema is doing the heavy lifting. The description's enumeration of asset_type values merely repeats what the schema already lists verbatim, adding no new meaning, and it says nothing about how query strings are matched or how max_results affects ranking.

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 ('search for a Yahoo Finance ticker symbol') and a clear scope ('by company name, fund name, or keyword'), plus the return content. It implicitly separates itself from symbol-first siblings like GetTickerInfo by saying 'Use this when you have a name but need the ticker symbol', though it never names a sibling explicitly.

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?

Three explicit 'Use this tool when' bullets cover the main scenarios (name without symbol, ETF/mutual fund lookup, disambiguation). This gives clear positive context, but there are no exclusions or named alternatives for cases where the agent already has an identifier.

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