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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds two useful behavioral facts: that the call returns both a price and a balance, and that a human-confirmation step should precede open_file. It says nothing about whether the quote is time-limited or reserved, which matters for a pricing check.

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?

A single dense sentence with the returned values front-loaded and the follow-up action second. No wasted wording, though the telegraphic noun-phrase opening is slightly less scannable than a verb-led statement.

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 only two fully documented parameters and no output schema, the description does explain what comes back (price and balance) and the workflow around open_file. However, it omits anything about the currency/unit semantics of the quote beyond 'credits' and whether the price can change between quote and open, leaving a modest gap for a spending decision.

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 100% and the enum for typ is fully documented in the schema, so the description carries no additional burden. It adds no meaning beyond the schema, which is the expected baseline here.

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 the concrete resource it returns: a credit price to open a file plus the account's credit balance, which is clearly distinct from siblings like get_file or open_file. It is phrased as a noun fragment rather than a verb+resource statement, but the intent is unambiguous.

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 explicitly sequences the call: invoke this and ask the person before calling open_file, giving a clear precondition for the mutating sibling. It stops short of stating when-not to use it or naming any alternative quoting paths, so it falls short of full when/when-not coverage.

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