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

Goes well beyond the readOnlyHint annotation by disclosing that the returned fields depend on the caller's permission scope — full material with hitl:read, only public_key/kid otherwise — and that private-key material is never exposed to confirmation-only keys. It also documents the Proof-account auth requirement, which annotations do not cover.

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-loaded with the core action and return behavior, with access requirements in a clearly separated block. The access paragraph has minor redundancy ('Authenticate this client... then call this tool again'), but every sentence carries necessary 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 carries the return-value burden and does so thoroughly, enumerating the fields returned under each permission tier and stating the auth prerequisite. Nothing an agent needs to call this correctly is missing.

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 there is a single required hitl_id param, so the schema already documents it. The description refers to 'a HITL config' but adds no format, sourcing, or lookup guidance for the ID beyond what the schema provides, so baseline 3 applies.

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 ('Get the encryption keypair for a HITL config'), clearly distinct from siblings like get_hitl, list_hitls, upload_hitl_keys, and delete_hitl_keys. An agent can identify the resource and operation 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?

Gives strong context: it explains the permission-conditional behavior (hitl:read vs confirmations:create) and states an explicit exclusion ('start_login does NOT open this tool') plus the auth prerequisite. It does not name sibling alternatives such as get_hitl or upload_hitl_keys, so routing guidance is good but not fully explicit.

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