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

Annotations already declare read-only, non-destructive behavior, so the description's extra value is in the private-data guarantee ('Credentials are never returned') and the meaning of the capability tri-state (true/false/'planned'). It does not cover auth requirements or rate limits, but the disclosure of what is and is not exposed adds real context beyond the annotations.

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?

Purpose is front-loaded in the first sentence and the rest is dense but information-bearing. The long capability parenthetical is the only heavy passage, and it earns its place by defining the tri-state values, though it could be tightened.

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 output schema, the description carries the burden of documenting the return shape, and it enumerates the fields (account ID, label, environment, broker type, server, status, last connection, errors, capabilities) precisely. Combined with the credential exclusion and sibling routing, an agent has everything needed to select and interpret this call.

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 per the rubric the baseline is 4. There is nothing for the description to disambiguate, and it does not need to.

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 ('List all broker accounts connected by the user') and clarifies what one unit represents ('a connection to a trading broker'). It is clearly distinguishable from sibling tools like create_broker_account or get_broker_account_state.

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?

Explicitly routes verification to the sibling ('Use test_broker_account to verify a connection'), giving a clear when-to-use-this-vs-alternative signal. It lacks explicit when-not conditions or prerequisites, but the guidance is concrete rather than implied.

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