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

Annotations only cover the read-only safety profile, and the description adds substantial traits beyond them: that only name/category/price/id are stored with NO description, that price is an unformatted bare string, that plan-excluded items will be rejected by install_extension, and that custom extensions require an organisation scope this key lacks.

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 core identity ('The extension STORE') and every sentence carries a distinct usable fact, but at roughly 130 words for a zero-parameter read it is longer than strictly necessary, and the editorial phrasing ('do not paper over them', 'say so instead of trying') is guidance padding rather than specification.

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?

No output schema exists, so the description must carry return semantics itself, and it does: the per-entry fields, the installed flag, and the availableOnYourPlan meaning. Combined with the routing and limitation notes, an agent has everything needed to call it and report results honestly.

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 is 4 and there is nothing for the description to disambiguate. It instead documents the shape of each returned entry (name, category, price, id, installed, availableOnYourPlan), which is return-value information rather than parameter semantics.

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?

Names the exact resource (the extension STORE) and its scope: every built-in extension, identical for every merchant. It explicitly distinguishes itself from get_installed_extensions and explains that custom extensions are excluded, so an agent can route correctly without opening a schema.

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 concrete trigger questions ('what can I add', 'do you have a WooCommerce integration') and the explicit counter-case ('what do I already have' -> get_installed_extensions). It also states the consequence of availableOnYourPlan: false (store hides it, install_extension refuses), which is exactly the when-not-to-act guidance an agent needs.

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