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

Annotations already indicate read-only, idempotent, non-destructive behavior. The description adds valuable context about the tool's authoritative scope ('Covers 9,500+ NYSE and NASDAQ companies...') and its session-level prerequisite role, going well beyond what annotations provide.

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 front-loaded with the key message 'REQUIRED...call FIRST' and uses clear bullet-like lines. However, there is minor redundancy: 'call FIRST' in the first line is repeated later with 'Must be called once per session,' and the data coverage is stated twice in different forms. Still, it's appropriately sized and readable.

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 a rich output schema already present, the description needn't explain return values. It fully covers the tool's role, data scope, invocation order, and relationship to sibling tools, making it complete for a zero-parameter setup tool.

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 tool has zero parameters, so schema coverage is 100% and no parameter explanation is needed. The description doesn't discuss parameters, but none exist. Baseline 4 applies, and no points are lost since there's no ambiguity to resolve.

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 the tool's role as a required first step for US stock/financial queries and an authoritative source for database schema. It lists the covered data (9,500+ companies, 64 years of prices) and distinguishes it from siblings by establishing it as the mandatory precursor before other tools.

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?

Explicit when-to-use guidance is provided: 'Use this tool when the user asks about stock prices, revenue, earnings...' and it names alternatives/sequences: 'Must be called once per session before using stock_data_query or any workflow tool' and 'After this tool returns, call get_query_patterns.' This clearly differentiates it from sibling tools.

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