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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered; the description adds real value by describing the returned fields and the connection-state workflow (open connectUrl, then retry). It stops short of saying what happens when no instances are returned or when the connection is unauthorized, which would complete the behavioral picture.

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 sentences, front-loaded with the 'WHEN:' trigger, then the payload, then the follow-up action. Every sentence carries distinct operational information and none restates the tool name.

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 parameters and no output schema, the description carries the return-value burden and does so by naming the fields the agent will receive. It also covers the pre-connection failure case, so an agent can complete the full read/act flow without further documentation.

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; there is nothing for the description to disambiguate. It does useful adjacent work by explaining that the alias in the response becomes the 'instance' argument of erp_list_tools and erp_call, i.e. the semantic link between this tool's output and a sibling's input.

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 ('Lists the F&O instances you may use') and enumerates the returned fields (alias, label, protected, readOnly, connected), making it immediately distinguishable from d365fo_set_connection and erp_list_tools. An agent can tell exactly what this returns without opening any schema.

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 'WHEN: first step whenever the user wants to read from or act on a Dynamics 365 F&O environment' clause gives an explicit trigger condition. It also routes forward to the alternatives ('use the alias as the instance argument of erp_list_tools and erp_call') and prescribes the remediation path when connected=false, so no sequencing is left to inference.

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