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

With no annotations, the description carries the full behavioral burden. It discloses that the operation is a read-only retrieval and that the response is a JSON array of past transitions with timestamps. It does not mention ordering, time range, pagination, or how an empty history is represented, but it still gives a reasonable picture of the 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?

The description is two concise sentences with no filler. The first sentence states the action and resource, and the second states the return shape and key field. Every sentence earns its place.

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 no-parameter getter, the description covers the essential information: what action is performed and what the response contains. Since an output schema exists, the context signal indicates return values are further specified elsewhere, so the missing details like ordering and time span are minor gaps.

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 input schema is an empty object, so there are no parameter semantics to document. The description adds no parameter detail, but none is needed; the 0-parameter baseline applies.

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 uses a specific verb ('Get') and names the exact resource ('the Vault's regime switch history'), making the tool's purpose clear. The second sentence confirms the output type. It doesn't explicitly contrast with sibling tools like get_vault_status or get_market_regime, but 'history' makes the intended scope evident.

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 implies when to use the tool: when the Vault's historical regime transitions are needed. However, it provides no explicit when-not-to-use guidance or alternative routing to get_vault_status/get_market_regime, leaving the agent to infer the distinction from the name and context.

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