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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so safety is covered. The description adds value beyond that by disclosing the data source ('Yahoo Finance via yfinance'), that no API key is required, and the shape of the return (60+ metadata fields), though it omits rate limits or caching behavior.

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 core action, then organized into scannable 'Use this tool when' and 'Works for' sections plus a source note. Every line is relevant, with only minor redundancy between the return-field sentence and the schema.

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 metadata fetch with an output schema present and safety fully covered by annotations, the description supplies everything an agent needs: purpose, target asset classes, symbols, source, and auth expectation. The only residual gap, the extraneous schema parameters, does not affect correct invocation for a 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 description's ticker-format guidance matches the symbol parameter but duplicates what the schema already documents, and it says nothing about the many other nested params (wholesaler_ids, source_resource_id, exclude_fillers, etc.) that appear unrelated to a Yahoo Finance lookup. With coverage reported at 0%, the description only partially compensates for the undocumented parameters.

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?

States a specific verb and resource ('Fetch the full Yahoo Finance profile') and enumerates the asset classes and the fields returned (sector, industry, market cap, P/E, etc.). It clearly conveys what the tool produces, but never names or contrasts against siblings like GetFundProfile, LookupTicker, or GetFinancials, so an agent must infer differentiation.

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?

Provides an explicit 'Use this tool when:' list covering three concrete scenarios (quick summary, sector/industry classification, price metadata). This gives clear context for use, but offers no when-not guidance and points to no alternative sibling for cases like detailed financials or fund-specific data.

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