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

The description adds value beyond the readOnlyHint annotation by stating it is 'Read-only' and explaining error behavior ('If a ticker returns no data'). However, it does not discuss rate limits or authentication, but given the annotation already covers safety, the additional context is sufficient.

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 detailed yet every sentence adds value. It is front-loaded with the main purpose, uses clear enumeration, and avoids redundancy. No unnecessary words.

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?

Given the tool has one parameter, no output schema, and rich annotations, the description fully covers input, failure behavior, and output data fields. It is complete for an agent to use correctly.

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 single parameter 'ticker' has 100% schema coverage, but the description adds extensive meaning: it specifies the exact format (native local-exchange symbol, examples, prohibited suffixes). This goes well beyond the schema's description.

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 clearly states it fetches a consolidated metrics snapshot for a single stock by ticker, listing specific data categories (identity, price, valuation, financials, description). It distinguishes from siblings like screen_stocks by focusing on a single stock and providing ticker format guidance.

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 explicitly says when to use the tool (fetch stock metrics) and when not to ('If a ticker returns no data, use screen_stocks...'). It also provides detailed ticker format instructions, preventing common mistakes like appending Yahoo suffixes.

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