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

The description announces write operations – 'create tables, insert, update' – and state that 'persists between calls', while annotations declare readOnlyHint=true. Those are directly in conflict, which is the rubric's condition for a 1. The rich quota/cost/batch-limit detail it does add (200 MB, 20 statements, $0.003 USDC) cannot offset the contradiction.

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 front-loaded sentence that opens with 'Your own private SQLite database that persists between calls', then colons into capability, limits and price. Dense with no filler, though the pricing clause could have been separated rather than strung into the same sentence.

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 and a 3-parameter surface, the description covers what an agent most needs: persistence semantics, wallet keying, batch cap, storage quota and per-call cost. It omits return/result shape and multi-statement transaction/atomicity behavior, which are the remaining gaps.

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 only 33% (`sql` and `params` carry no descriptions), so the description must compensate. It does partially: 'up to 20 SQL statements per call (parameters supported)' explains the batch limit and parameter binding that the schema leaves implicit. It still never clarifies how the single `sql` field relates to the `statements` array, so it is adequate but incomplete.

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 set and resource: 'Your own private SQLite database that persists between calls... create tables, insert, update and query'. The persistence model and wallet-keying are clear. It does not differentiate itself from the sibling `sql` (or `sql_generate`/`storage`), so it stops short of a 5.

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?

Gives operational constraints (up to 20 statements per call, 200 MB per wallet, $0.003 USDC per call) that shape usage, so usage is implied. But it never states when to choose this over the sibling `sql` tool or when not to use it, and no preconditions (schema creation order, wallet funding) are spelled out.

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