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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety bar is low. The description still adds real context beyond them: it identifies the authoritative upstream (official kazpost.kz domain) and discloses that the call is free, which tells an agent there is no billing/auth cost to worry about. It omits failure behavior for an invalid or unknown barcode.

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 covering action, input, output and source, plus a two-word cost note. Nothing redundant, nothing padded.

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 a single-parameter read-only tool with a fully documented schema, the description covers purpose, source and the shape of the result (status + route events), which compensates for the absent output schema. Minor gap: no indication of what happens when the barcode is not found or the parcel is unknown.

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% and the schema already specifies the 13-character barcode format with an example (RR123456789KZ). The description only restates 'by barcode' and adds the domestic-number allowance already implied by the schema, so it does not meaningfully extend 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 specific verb (track) and resource (a Kazakhstan Post parcel) plus what comes back (status + route events) and the upstream source (official track.kazpost.kz). No sibling in the list (fx_rates, weather, lei_lookup, etc.) overlaps with parcel tracking, so differentiation is inherent.

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 'by barcode' phrasing implies the prerequisite and thus when the tool applies, but there is no explicit when-to-use/when-not guidance or named alternative for parcel lookup. Usage is inferable rather than stated.

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