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

Goes well beyond the readOnly/idempotent annotations: it explains that range-dated items count toward every spanned year so bucket sums can exceed dated_items, discloses the accompanying dated_items/undated_items/year_range fields, and notes the absence of amira_url because years lack authority pages. This is exactly the behavioral context annotations cannot carry.

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 tightly packed sentences with no filler; the core purpose is front-loaded before the counting semantics and the amira_url caveat. Every sentence carries non-redundant information.

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 output schema, the description compensates by naming the returned fields (dated_items, undated_items, year_range) and the missing amira_url, and by spelling out the counting semantics. Nothing an agent needs to interpret or call the tool is absent.

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 83%, so from/to/bucket/sort/limit are already documented in the schema. The description reinforces the year-vs-decade bucket semantics but adds no syntax, default, or range detail beyond the schema, making the baseline 3 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?

States a specific verb+resource ('Date histogram of the research items') and scope ('how many fall in each year (or decade) of their content dates'), immediately distinguishing it from sibling item-listing tools like search_research_items. An agent can tell what it produces 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?

Names concrete use cases ('coverage-over-time and most-covered-year questions') and links the output back to the year_from/year_to filter of search_research_items, giving clear context for when to reach for this tool. It stops short of explicit when-not or alternative-tool routing, so it lands just below the top band.

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