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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds real value on top by disclosing what the returned rules contain (permitted assets, maximum order size) and by stating it is not a mutation path. It doesn't cover failure behavior for an unknown portfolio_id, which keeps it from a 5.

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?

Front-loaded with the verb+resource, then usage, then the behavioral constraint, then the single argument. Four short lines with no padding; even the Args block earns its place by adding the UUID format.

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?

The tool is a simple single-parameter read, an output schema exists so return structure needn't be described, and the description still summarizes what the rules express and what the tool cannot do. Nothing an agent needs to invoke it correctly is missing.

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 description coverage is 0%, so the description carries the burden, and it does specify that portfolio_id is a UUID rather than an arbitrary string or name. With only one required parameter, this is nearly sufficient, though it omits where to obtain the UUID.

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 ('Read the order limits for a portfolio') and immediately clarifies the boundary against siblings: it is a prerequisite check, not a mutation. An agent can distinguish it from add_transaction and edit_order 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?

Explicitly says when to call it ('Call this before add_transaction on a buy, sell, short, or cover'), naming both the alternative tool and the exact triggering conditions. It also rules out misuse with 'This tool cannot change the rules.'

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