authenticate

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

Annotations only declare readOnlyHint=false and idempotentHint=true, and the description adds real behavioral context: the effect is session-scoped state mutation, re-invocation replaces rather than accumulates targets, and credentials have no per-call analog elsewhere. It still does not say whether credentials are validated eagerly at call time or lazily on first use, nor what a successful call returns.

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 short sentences, front-loaded with the action and followed by the two constraints an agent most needs (session scope, replacement semantics). No filler or repetition, though the parenthetical '(or replace)' is partially restated by the 'Calling this again replaces the session's target' sentence.

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 and nine parameters including writeOnly secrets, the definition should say more about outcomes: whether bad credentials fail here or later, and what a caller can assume after success. The session/replacement model is well covered, but the success-failure contract is left unstated.

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 89%, so parameters like stage, verify_ssl, ca_bundle_path, prefer_zen_api_key, and region_or_url are already documented in detail in the schema. The description mentions no parameters at all, adding nothing beyond the structured fields. Baseline 3 is appropriate because the schema carries the parameter burden.

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?

The description uses a specific verb and resource ('Establish (or replace) this session's target environment and credentials') and explicitly positions the tool against every sibling: all other tools operate against the current authenticated session. An agent can identify this as the session-bootstrap tool 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?

It states the prerequisite relationship clearly (other tools depend on the current session, and there is no per-call credential parameter, so this call is the setup step). It also warns that repeat calls replace the target and that v1 allows only one active target per session, which is an implicit exclusion against concurrent multi-target use. It does not spell out what to do when authentication fails or when a target must be switched mid-workflow.

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