recon_diff

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

Beyond the readOnlyHint annotation, it discloses precise behavior: missing left keys in right produce an error (FK broken-chain isomorphic), the tolerance formula is absolute half-grid (default 0.5) plus relative 1e-9, ratio handles multiplier transcription, and omitted values select pure key-domain reconciliation.

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?

The description is dense but every clause adds operational value: purpose, roles, error semantics, tolerance formula, ratio behavior, optional mode, and prerequisite. No filler or repetition of schema names.

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?

For an 8-parameter tool with no output schema, it covers input roles, error behavior, tolerance, optional reconciliation mode, and table discovery. The only notable omission is the shape or semantics of the result/return value, which would round it out.

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?

Even though schema coverage is 100%, the description significantly enriches parameters: it defines left as detail/checked and right as baseline/master, explains tolerance's default and formula, gives a ratio example (quality coefficient 1.4), and clarifies that omitting leftValues/rightValues yields FK-style reconciliation.

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 opens with '跨表对账（L3）' and defines the exact operation: align two tables by declared key columns and compare value columns cell by cell. It specifies left vs right roles and even names the prerequisite list_tables, making the tool's unique role among siblings evident.

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 gives clear context for use: current workspace, two-table reconciliation, left/right orientation, and the explicit prerequisite '先 list_tables 拿表名与列名'. It does not name alternatives or when-not-to-use conditions, so it stops short of a 5.

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