history

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

With no annotations, the description itself carries the behavioral disclosure: it declares the operation read-only, specifies event-time ordering, and explains that the response contains every historical value for the key. It stops short of describing the exact response shape or missing-key behavior, but the essential side-effect profile is clear.

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 a single dense sentence with no redundancy; the core behavior, ordering, and read-only nature are all front-loaded. The 'plain vector store' clause is slightly promotional but still communicates the tool's differentiating value.

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?

The operation is simple: one key parameter, one read-only query. The description provides a conceptual return value (full timeline, every value, event-time order) that compensates for the absent output schema. It omits pagination/limits and explicit alternatives, but these are secondary for a one-parameter read-only lookup.

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?

Schema description coverage is 0%, so the description must supply the meaning of the sole key parameter. It does so by placing key as the subject of the timeline, making it clear that the parameter identifies whose history is returned. It does not elaborate on format or allowed values, but the schema already constrains it to a string.

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 a precise operation: retrieve the full validity timeline for the supplied key, consisting of every value it has held in event-time order. This clearly distinguishes it from sibling recall/provenance/as_of 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?

The audit-trail framing implies use when an agent needs the complete historical record of a key rather than a single value. However, it never explicitly states when to prefer history over related siblings such as as_of, provenance, recall, or audit_bundle, and no exclusions are given.

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