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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), but the description adds a non-obvious behavioral contract that annotations cannot express: root scalar fields come back in full while nested entities are stubs flagged expandable=true, requiring a follow-up call with 'path'. Without this, an agent would misread a partial response as complete. It also discloses rights-based filtering of the returned fields.

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 dense sentences with no filler. The core capability and its syntax example are front-loaded, and the expansion workflow follows immediately after, so the agent hits the most decision-relevant information first.

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 no output schema, the description carries the return-shape burden and does so well (scalar root fields, stub nested nodes, expandable flag, rights filtering). It is complete enough to call correctly, though it says nothing about limits on selector depth/size or failure behavior for an invalid path.

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 description coverage is 100%, so the baseline is 3; the description adds meaning beyond the schema by showing the 'fields' selector grammar ('{id, firstName, tags{id, text}}') and explaining that 'path' is used to expand a stub on a repeat call. The schema's own path example ('orders.product') is only slightly extended, so the gain is modest but real.

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 states a specific verb+resource: it returns the exact set of fields an operation's 'fields' selector supports, with a concrete syntax example. That is far more precise than a generic 'get schema' statement, but it never names or contrasts with its closest siblings (get_operation_schema, get_extended_filter_schema), so the agent must infer the boundary itself.

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 gives real usage context: the result respects the current admin's rights, and nested nodes are expanded by re-calling the tool with 'path'. That tells the agent how to drive the tool iteratively. It stops short of saying when to prefer this over get_operation_schema or the filter-schema tool, so no explicit exclusions are offered.

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