tally_alter_voucher

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

Annotations declare a destructive write, and the description goes well beyond them: it explains the two-step preview/confirm model, that this call changes nothing and returns a confirmToken, that no preview is written until confirmation, and that confirmation is refused if the voucher moved in TallyPrime since preview (which would otherwise create a duplicate). That concurrency/staleness behavior is not inferable from annotations or schema.

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?

Front-loaded with the action, then prerequisites, then the write-safety warning, so an agent can stop reading early if needed. It is dense and slightly repetitive with the capitalized emphasis, but nearly every sentence carries non-obvious operational information, so little 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?

For an 11-parameter, high-risk mutation with no output schema and no top-level return documentation, the description covers what an agent must know: required inputs, replacement semantics, the preview/confirm handshake, the stale-write refusal, and the stock-journal limitation. Nothing critical about invoking it correctly is missing.

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 coverage is 91%, so the baseline is 3, but the description adds genuine meaning: the full-replacement semantics ('every line, not only the changed ones'), the distinction between currentDate (as it is now) and date (as it should be afterwards), and the item-invoice caveat for `items`. It does not, however, elaborate on the nested bill/cost-centre structures, which the schema handles.

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?

Opens with a precise verb+resource ('Change an EXISTING voucher in TallyPrime') and enumerates what can change (lines, amounts, date, narration, reference). It also carves itself away from siblings by noting that stock journals cannot be altered here and must instead be cancelled/deleted and re-posted, which separates it from tally_create_voucher and tally_cancel_voucher.

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?

States the prerequisites explicitly (the voucher's guid and current date, both from tally_get_vouchers), the shape of the payload (the COMPLETE voucher, not just changed lines, including `items` on an item invoice), and the exclusion (stock journals). It also names the follow-on tool (tally_confirm_write with the token) and the condition for using it.

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