sap_connect_existing

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

Annotations already declare this a safe read operation, so the bar is lower; the description still adds real behavioral context by noting it attaches to SAP Business Client / embedded SAP GUI sessions, that indexes originate from sap_list_connections, and that scripting-disabled connections are un-attachable.

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, action front-loaded, no filler; the distinguishing condition and the failure constraint each earn their place.

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 an output schema present, return values need no explanation, annotations cover safety, and the description supplies the indexing model plus the scripting-disabled limitation. Only the explicit contrast with sap_connect for the non-logged-in path is absent.

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 coverage is 0%, so the description carries the burden and does so: it explains that connection_index=0 and session_index=0 target the first open session and that index values come from sap_list_connections. It does not describe what happens with out-of-range or missing indexes.

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?

States a specific verb and resource ('Connect to an already open SAP session') and immediately disambiguates scope with 'Use this when SAP is already logged in', which distinguishes it from the sibling sap_connect that presumably establishes a new connection.

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?

Gives a clear when-to-use condition ('SAP is already logged in') and frames it as the most common starting point, plus a hard constraint: a connection with scripting_disabled=true cannot be attached. It stops short of explicitly naming the alternative tool (sap_connect) for the not-logged-in case.

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