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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the agent knows this is a safe, sandboxed read. The description adds the useful fact that the tool is 'Free', but does not clarify what 'checks' means or whether this returns static content versus live account data. With annotations covering the safety profile, a 3 is appropriate.

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?

One compact sentence with no filler, and the key content areas are front-loaded. It is arguably too terse given the ambiguity of 'checks', but nothing in it is wasted.

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?

An output schema exists, so the description is not obligated to explain return values, and a parameterless read tool has a small contract to document. The remaining gap is the vague phrase 'what Privi Guard checks', which an agent must resolve by calling the tool, but overall it is complete enough.

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 there is nothing for the description to disambiguate beyond what an empty schema already communicates. Baseline of 4 applies for a parameterless tool.

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 identifies the resource (Privi Guard pricing information) and enumerates the three content areas it covers: what Guard checks, what it costs, and how receipts work. That is clearer than the bare name 'guard_pricing'. It does not, however, differentiate itself from the sibling guard_receipt or ledger_pricing, leaving the agent to infer the boundary.

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?

There is no guidance on when to call this versus the many adjacent pricing/receipt tools such as ledger_pricing, guard_receipt, or guard_balance. The description only states what the tool contains, not the condition under which an agent should reach for it.

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