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

Annotations already establish a safe read (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, yet the description adds genuinely useful behavioral context: each kit is described by a public manifest, packaged source is not distributed yet, and no kit carries a price. That manages expectations about artifact availability beyond what annotations convey.

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 usage trigger 'when the problem is on the device rather than on the server' is stated twice in near-identical wording, which is wasted space in an already long description. The opening 'Native work that is already finished' is also a fragment that adds little. Content is informative but not tightly edited.

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 zero-parameter, read-only list tool with no output schema, the description supplies nearly everything needed: what a kit is, when to reach for it, and the current limitations (manifests public, source undistributed, no pricing). The only gap is that it never hints at the shape or contents of the returned manifest list.

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?

The tool takes zero parameters, so the baseline of 4 applies. The description does not need to explain any parameter semantics, and it adds none, which is correct behavior for a parameterless list operation.

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 defines the resource precisely – a Native Kit is 'packaged iOS and Android source with the exact dependency pins, permissions, entitlements, plist keys and protected configuration' – and explicitly contrasts it with a Capability, which lets an agent distinguish it from trustycap_list_capabilities. However, the description never states the verb ('list' or 'returns a collection'), relying on the name/title for that, so it stops short of a fully self-contained purpose statement.

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?

Clear context is given: use when the app must ship to the App Store/Play Store or the problem is device-side rather than server-side, with concrete examples (background location, native sign-in, store billing, secure storage). It does not name sibling alternatives such as trustycap_get_native_kit for fetching a specific kit or trustycap_list_capabilities, so the agent must infer the routing.

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