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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description still adds genuine behavioral context beyond the annotations: it discloses the return contents (provider list, key prefix, last-used date) and explicitly states the actual key is never returned, which is meaningful for an agent reasoning about secret exposure.

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 tight sentences, zero boilerplate: what it lists, what each entry contains, and the security guarantee. The most decision-relevant fact (it is a status listing, not a key retrieval) is front-loaded.

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 carries the return-shape burden and discharges it by naming the fields returned. It is complete enough to call correctly; the only gap is that the empty input schema is never confirmed (i.e. that no provider filter argument is accepted).

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?

The tool takes zero parameters, so per the rubric the baseline is 4. There is nothing to under-document and the description does not introduce pseudo-parameters or filtering options that the empty schema would contradict.

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?

Specific verb (list) plus precise resource (configured BYOK provider keys) with scope details: which providers, prefix, last-used date. It is distinguishable from siblings like set_byok_key and delete_byok_key by name alone, but it never explicitly acknowledges those siblings or contrasts itself with list_api_keys/list_mcp_keys.

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?

Usage is only implied: an agent can infer this is the read-side counterpart to set_byok_key/delete_byok_key, but the description never states when to call it (e.g. to audit configured keys before setting or deleting one) or any prerequisites. No alternatives or exclusions are named.

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