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

The description confirms the retrieval operation but relies on annotations for safety profile (readOnlyHint: true). It adds minimal additional behavioral detail beyond what the structured data already provides, making it solid but not exceptionally rich.

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 definition is brief and highly efficient. The two sentences cover purpose and parameter behavior without redundancy, placing the most important logical constraint (the 'key' usage) prominently.

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 clear semantic explanation of parameters and strong safety annotations, the definition provides everything necessary for an agent to select and correctly invoke the tool based on the task.

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?

Given the 0% schema description coverage, this description is vital. It thoroughly explains the operational logic of the 'key' parameter—how it changes the behavior from a full list retrieval to a specific field lookup—adding crucial semantic 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?

The description clearly identifies the action (Get), the resource (custom fields of a post), and the primary method (by ID). It successfully distinguishes itself from other sibling tools like `wp_get_post` or `wp_get_posts`.

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?

It provides explicit usage rules for the optional 'key' parameter: provide it to target a single field, or leave it out to return all fields. This directs the agent's intent perfectly.

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