Get the DataLens instance

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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds real value beyond that by framing the call as a 'safe auth probe', telling the agent that a failure here signals bad credentials rather than a destructive side effect. It still does not describe the shape of the returned instance.

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?

A single short sentence with no filler; the core noun phrase comes first and the clarifying use case is appended in parentheses. Nothing could be trimmed without losing meaning.

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?

For a zero-parameter, no-output-schema tool the description is minimally sufficient, but with no output schema the reader would benefit from knowing roughly what the 'instance' payload contains (id, name, endpoint) so they can use the result. As written it is adequate but thin.

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 the baseline is 4. The description correctly implies the operation is parameterless by scoping the result entirely to 'the credentials', requiring no argument-level clarification.

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 identifies a specific resource, 'the DataLens instance the credentials reach', which tells the agent this returns the tenant/instance bound to the current credentials. It is a noun fragment rather than a verb+resource statement, but combined with the name and title the operation is unambiguous. It partly differentiates from siblings like datalens_cloudenvironments_get by tying the result to the caller's credentials.

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?

The parenthetical '(a safe auth probe)' implies the primary use case: verifying that credentials are valid and reach a DataLens tenant. However, no explicit when-to-use/when-not-to-use guidance or alternative tools are named, so the routing guidance is inferred rather than stated.

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