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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds genuinely useful behavior beyond that: the catalogue exceeds 200 entries so the listing is capped and filterable, not exhaustive, and it names the valid categories. It could have noted the default/cap explicitly, hence 4.

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?

Front-loads the purpose in one sentence, then usage, then constraints and categories. Slightly long with the trailing category list duplicating the schema, but every section is functional and no sentence is filler.

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?

No output schema exists, and the description compensates by describing the returned row fields. Combined with usage routing, capping behavior, and category list, an agent has everything needed to call and interpret this tool.

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 100% (limit range and category enum documented in the schema), so the baseline is 3. The description reinforces that filtering is by category but adds no syntax or semantics beyond the schema.

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 ('compact index of what OpenChainBench measures') and precisely enumerates the row shape (slug, title, category, metric, value, leader). It is clearly distinguishable from search_benchmarks and get_benchmark, which are named separately.

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?

Gives explicit triggers ('what does OpenChainBench cover?') and an explicit alternative with rationale: search_benchmarks for provider/chain questions because it ranks against their words and 'costs far less to read.' It also routes to get_benchmark for drilling in.

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