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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior. The description adds important access behavior—FULL TIER ONLY and the UPGRADE_REQUIRED error on the free endpoint—plus the free alternative. It does not describe rate limits or return values, but an output schema exists.

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?

Three sentences, front-loaded with the tier restriction, then the use case, then the error/alternative. Every sentence carries operational information and there is no repetition.

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 zero-parameter, read-only analysis tool with an output schema and annotations, the description covers the key missing context: tier gating, the free-endpoint error, and the sibling alternative. Nothing essential for correct invocation is omitted.

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?

There are zero parameters, so the schema imposes no parameter-documentation burden; the baseline for 0 params is 4. The description adds no parameter details, which is appropriate.

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 names two concrete operations—stress-testing arbitrary tickers and constructing a low-drawdown portfolio—and explicitly distinguishes the free sibling portfolio_stress_test by its limited universe. An agent can identify the tool's function without opening the schema.

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?

It gives an explicit when-to-use condition ('Use when you want to stress... or construct...'), states the full-tier requirement, and names the free alternative for SPY/TLT/GOLD/BTC books. It also warns that the free endpoint returns UPGRADE_REQUIRED, so the agent knows the access boundary.

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