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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description corroborates this with 'opens nothing by itself', so no contradiction. It adds real value beyond the annotations by disclosing the return format (step-by-step screens, buttons, fields) and the handoff to browser tools, plus the external API constraint. It does not say how the guide is targeted to a specific invoice despite taking zero parameters, which is a notable remaining gap.

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 behavior is front-loaded in the first sentence, and every later clause (no action taken, browser handoff, API availability) carries information. The API sentence is slightly redundant in construction ('Housecall Pro's official API: Housecall Pro has a public REST API...') and could be tightened 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?

With no input parameters and no output schema, the description carries the full burden and meets it: it says what is returned (step-by-step instructions with screens, buttons, fields), that no side effect occurs, and which tools perform the actual action. An agent has everything needed to decide to call it and what to do next.

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?

There are zero parameters, so the baseline is 4 and there is no schema content for the description to duplicate. The description could have clarified that the specific invoice must be identified in the conversational request rather than through arguments, but its absence is a minor omission for a no-arg tool.

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 names a specific verb and resource and immediately disambiguates the ambiguous name 'send_invoice' by stating it 'Returns how to do it in Housecall Pro step by step (screens, buttons, fields) and opens nothing by itself.' An agent can tell this is a guidance tool, not an executor, without opening anything else.

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 a clear operating sequence: call this to get the step-by-step, then perform the action with the cotlet_browser_* tools in the user's Cloud Browser. It also explains why (API restricted to MAX plan), which is useful routing context. It stops short of explicitly excluding write-style siblings like housecall_pro_create_invoice by name, so the boundary is implied rather than stated.

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