opensearch_histogram

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

No annotations available, so the description carries full burden. It discloses that fine intervals over long ranges are rejected for resource protection, but does not explicitly state that the tool is read-only or describe other behavioral traits like idempotency or authorization needs. Some transparency provided, but not exhaustive.

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 concise sentences with no filler. First sentence states purpose, second gives primary usage guideline, third warns of a constraint. Front-loaded and 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?

With output schema present, return values need no elaboration. The description covers key usage nuances (range necessity, interval behavior) and constraints. Minor omission: explicit mention that it produces histograms, but purpose implies that. Good completeness for the tool's complexity.

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 coverage is 100%, so baseline is 3. The description adds meaningful context beyond schema: mandates from_ts/to_ts usage, recommends 'auto' interval, and explains rejection of fine intervals. This extra guidance raises the score.

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 'Event count over time' with specific verb (count) and resource (events over time), and emphasizes the range requirement which distinguishes it from search or raw data retrieval tools. Siblings like opensearch_search, opensearch_terms, etc., have different purposes.

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?

Explicitly advises to 'always specify from_ts and to_ts' and recommends using interval='auto' when unsure. Warns that fine intervals over long ranges are rejected pre-query, providing clear when-to-use and safety constraints.

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