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

The description discloses materialized snapshot behavior, projection to this model's grain with nulls outside source coverage, non-automatic refresh, and per-link failure handling that does not touch stored values. These details go well beyond the annotations (readOnlyHint=false, destructiveHint=false) and there is no contradiction between text and annotations.

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 description is long but dense and well organized: it front-loads the core concept, then explains the two op modes, then points to sibling tools, and ends with the critical read-only-key limitation. Every sentence carries useful information with no filler.

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 description covers creation, retargeting, refresh behavior, permissions, failure semantics, and the resulting referenceability of the line, which is strong for a dual-mode tool. However, there is no output schema and the description does not state what a successful link or refresh returns, leaving a modest gap for an agent expecting a response shape.

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?

Although the schema already documents all 10 parameters with 100% coverage, the description adds meaningful operational semantics: link vs. refresh behavior, uid retargeting, uids as a refresh filter, the name default to the source item, parent container types, source_model_id as the model to read from, and the summary's role in version history. This goes well above the baseline for high schema coverage.

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 action ('Link this model to an item of ANOTHER Layerz model') and a concrete resource, with the Excel linked-workbook analogy making the concept immediately understandable. It also names the sibling tools layerz_external_ref_status and layerz_unlink_external_ref, so an agent can distinguish this tool from related ones.

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 explicitly directs the agent to read links with layerz_external_ref_status and detach one with layerz_unlink_external_ref, giving clear routing to alternatives. It also gives crucial when-to-use constraints: refresh is the ONLY way values update, it requires read access to the source model, and it is unavailable for read-only API keys.

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