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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, destructiveHint=false), yet the description still adds meaningful context: the operation mirrors the woocommerce-mcp-server `get_customer_meta` method and runs on local WordPress authentication, so no WooCommerce REST API keys are needed. That auth disclosure is genuinely useful and goes beyond structured fields, though the return shape is not described.

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?

Two tight sentences with the purpose front-loaded. The second sentence about mirroring and authentication is slightly implementation-oriented but carries real operational value, 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?

The tool is a simple three-parameter read with full schema coverage and complete annotations, so most requirements are met. However, with no output schema there is no statement of what metadata is returned (e.g., a key/value list or single value when metaKey is supplied), which leaves a real gap for the calling agent.

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 the schema already documents site_id, customerId, and metaKey in detail, including the important instruction to call list_sites first. The description merely restates the optional meta-key filtering and adds no format, casing, or wildcard semantics beyond what the schema provides, so the baseline of 3 applies.

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 names a specific verb and resource ('Retrieves WooCommerce customer metadata') and adds a scope qualifier ('optionally filtered by meta key'), which is enough to distinguish it from the mutation siblings (wc_update_customer_meta, wc_delete_customer_meta) and from the broader wc_get_customer. It stops short of explicitly contrasting those siblings, so it is clear but not fully differentiated.

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?

Usage is implied by the optional metaKey filter, which tells the agent it can narrow results rather than fetch everything. There is no explicit guidance on when to prefer wc_get_customer over this tool, or what happens when no key is supplied.

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