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

Annotations already declare read-only/idempotent/non-destructive, and the description adds substantial context on top: what the response contains (both sides, difference history and its start date, on-hand by source, open allocations, findings with units and evidence plus a suggested fix) and the exact finding taxonomy. The permission requirement is also disclosed, which annotations do not cover.

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?

Purpose is front-loaded in the first clause, followed by return contents and the finding taxonomy. The long enumerated findings list makes it a single dense sentence, but each item is informative enough to earn its place; light restructuring would improve it.

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, the description carries the return-value burden and does so thoroughly: both sides of the comparison, difference history, source breakdown, allocations, and structured findings. Together with the permission note and the closed-world/read-only annotations, an agent has everything needed to call it correctly.

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 100%, so both 'sku' and 'warehouse' are already documented in the schema, including the optionality rule for warehouse. The description adds only the framing 'one product at one 3PL warehouse', which the schema already conveys; baseline 3 applies when the schema carries parameter meaning.

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 precise verb ('Explain why ... differs') with a fully scoped resource: one product, one 3PL warehouse, SKU.io on-hand/available vs. the 3PL, sourced from the latest inventory comparison. This clearly separates it from reporting siblings like get_inventory_levels and from the mutating adjust_inventory.

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 clear context for invocation ('from the latest 3PL inventory comparison', 'one product at one 3PL warehouse') and flags the required inventory.index permission. It stops short of naming alternatives (e.g., use get_inventory_levels for raw numbers, adjust_inventory to fix) or stating when not to use it.

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