List search engines and their status

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: engines can be temporarily 'benched' after repeated blocks, which explains otherwise confusing absence from results. It does not cover rate limits or output shape, so it lands just short of a 5.

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?

Two sentences, zero filler, with the content of the listing front-loaded and the actionable routing ('pick explicit engines for web_search') placed second. Every clause 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?

There is no output schema, so the description carries the return-value burden and does it by enumerating the four fields returned. Combined with the annotation-backed safety profile and the schema-documented format parameter, an agent has everything needed to call this correctly.

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% and the single 'format' parameter is fully documented in the schema, so the description correctly stays out of it. Baseline 3 applies since the description adds no syntax or default-value detail beyond what the schema already provides.

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 and resource ('Show every engine this server knows about') and enumerates exactly what the listing contains: indexed content, API-key requirement, tier, and current health. It also routes the agent toward web_search as the downstream consumer, so it is distinguishable from the other search/index siblings.

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 two concrete use cases: selecting explicit engines for web_search and diagnosing an empty result list. That is clear when-to-use guidance, but it stops short of an explicit exclusion or comparison against the other siblings (research, search_index, local_index).

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