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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the description only needs to add context — and it does, noting the regime is 'already-computed' and public-only rather than live or paid. It does not say how fresh the regime is or what the response contains, but the safety profile is fully covered.

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?

Two sentences, both load-bearing: the first gives the trigger condition, the second gives the returned artifact and its scope limits. Nothing is repeated from the title or annotations, and the usage cue is front-loaded.

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 no parameters and no output schema, the description carries the burden of describing the return value, and it does so at a high level ('latest already-computed public market regime'). It could say more about the shape or staleness of that regime, but for a zero-arg lookup tool an agent has enough to call it 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 tool takes zero parameters, so there is nothing for the description to disambiguate; the baseline of 4 applies. The description correctly implies no input is required by framing the call purely as a retrieval.

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 gives a specific verb and resource: it returns Bobby's latest already-computed public market regime, scoped to the broad US market. It also draws a boundary against paid tiers ('does not expose paid alerts or portfolio data'), which helps distinguish it from sibling tools, though it never names an alternative outright.

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 opening clause is an explicit trigger: use it when the user asks what is moving the broad US market or whether the tape is risk-on, risk-off, or mixed. The trailing clause provides a form of when-not (no paid alerts, no portfolio data). It stops short of 5 because no alternative tool is named for adjacent questions.

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