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

Annotation readOnlyHint=true is consistent with the declaration that it 'opens nothing by itself', so no contradiction. Beyond the annotations, the description discloses the return shape (step-by-step guidance covering screens, buttons, fields) and explains the underlying constraint that Joist has no public API, which justifies why instruction-returning is the behavior. What it does not cover is the granularity or length of the returned steps.

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?

The core purpose is front-loaded in the first sentence, which is good. However, the closing sentence about Joist's official API, complete with a verification date, is justificatory backstory rather than something the agent needs in order to invoke the tool correctly, so it dilutes an otherwise tight definition.

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, non-destructive guidance tool with no output schema and annotations already covering the safety profile, the description supplies everything needed: what it returns, that it mutates nothing, and which sibling tool family performs the actual browser action. The only missing piece is routing against the near-identical 'add_client' sibling.

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 has zero parameters and the schema is fully closed (additionalProperties: false), so there is no parameter meaning for the description to add. Baseline 4 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?

The description makes the crucial correction that this tool does not itself add anything: it 'Returns how to do it in Joist step by step (screens, buttons, fields) and opens nothing by itself.' That is a specific and useful verb+outcome statement that an agent could not infer from the name 'add client'. It stops short of distinguishing itself from the unprefixed sibling 'add_client', leaving that ambiguity unresolved.

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 workflow explicitly: get the steps here, 'then do it with the cotlet_browser_* tools in the user's Joist Cloud Browser.' That tells the agent what to do before and after. It does not say when to prefer this over the similarly named 'add_client' or 'cotlet_app_guide' siblings, so guidance is clear but not complete.

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