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

The annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, and the description usefully reinforces this with 'opens nothing by itself' and describes the return content (screens, buttons, fields). However, the closing paragraph about Fortnox's public REST API, scopes and licence registration describes a different integration path that this tool does not use, which risks making an agent think this call requires API credentials or performs an API write.

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 first two clauses are tight and front-loaded, but roughly half the text is an off-topic aside about Fortnox's REST API, scopes and licence requirements that has no bearing on invoking this tool. That sentence neither earns its place nor is harmless, since it introduces a misleading auth narrative.

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, read-only helper with no output schema, the description does cover what comes back (step-by-step screens, buttons, fields) and what to do next. It omits prerequisites that matter in practice, such as whether a Fortnox browser session must already be open, and says nothing about the guide's scope (which invoice, what variations).

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 there is no parameter semantics to add; the baseline for a 0-parameter schema applies. The description does not invent or misdescribe any inputs, which is the correct behavior here.

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 states a concrete verb and resource (send a Fortnox invoice) and immediately corrects the expectation set by the name: it returns a step-by-step guide and 'opens nothing by itself'. That correction is the single most important thing an agent needs, and it is present. It stops short of contrasting with the sibling fortnox_create_invoice, so an agent still has to guess whether to use this or the API-backed creator.

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 gives an explicit handoff: after getting the guide, perform the action 'with the cotlet_browser_* tools in the user's Fortnox Cloud Browser'. That is a real when-to-use/when-next instruction rather than an implication. It does not state when NOT to use this (e.g. versus fortnox_create_invoice for API-based creation), which keeps it out of 5 territory.

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