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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is largely covered. The description adds genuine value beyond them with the economic note 'Does not spend sats', which matters in a payment-oriented toolset. It stops short of describing freshness or catalog scope.

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?

Two short, front-loaded sentences with zero filler; the scope statement precedes the cost clarification, which is the right ordering for an agent scanning for fit.

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 return values need no explanation, and the single optional param plus rich annotations leave little ambiguity for such a simple tool. A brief note on how current the counts are would make it fully complete.

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 single enum parameter is fully documented in the schema, so the baseline is 3. The description's 'by protocol' and the implicit whole-catalog default align with the schema but add no new syntax or format detail.

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 (counts) and resource (public listing counts) scoped by protocol, which cleanly separates it from action-oriented siblings like buy, quote, and spend_summary. It lacks an explicit named alternative, but the resource/verb pairing 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?

The sentence 'Does not spend sats' implies this is the free, safe way to inspect the catalog versus paid siblings, and the schema notes that omitting the filter counts everything. However, no sibling is named and no explicit when-to-use/when-not rule is stated, so guidance is only implied.

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