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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds genuinely useful behavior beyond that — it validates credentials, waits on the upstream provider (latency warning), and can surface upstream failure as ordinary data rather than an error. That failure-as-data disclosure is exactly the kind of gotcha an agent needs.

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 with zero waste: the first front-loads what the tool does and how, the second adds the behavioral caveats (slowness, failure-as-data). No filler or restatement of the name.

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 annotations covering the safety profile and the description covering latency and the failure-as-data return behavior, an agent has what it needs to call this correctly despite the absence of an output schema. Return structure is left implicit, but the main return gotcha is flagged.

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% and both required parameters are fully described with ID patterns, so the schema carries the parameter burden. The description adds only the loose implication that modelProviderConfigID holds the credential being validated — no syntax or format beyond the schema, matching the baseline 3.

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 — "Fetches the provider's live model catalog" — and distinguishes itself from the sibling config routes by revealing the mechanism: validating the configured credential and probing /models. An agent can tell this apart from model_providers_get/list without opening either 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?

It positions itself against "the other model provider config routes" and flags that it is slower, which implies when it is and isn't the right choice (live data vs. cheap config reads). It stops short of naming a specific alternative (e.g. model_providers_get or models_list) or an explicit when-not-to-use condition, so it is clear context rather than full routing guidance.

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