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

Annotations already declare readOnly/idempotent/non-destructive; the description adds non-obvious runtime behavior: an O(1M+ chunks) expense warning, dual-form label ID expansion (`@SYS124480` and `@SYS:124480`), and the extension-handler exclusion. All fully consistent with the annotations — no contradiction.

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?

Six compact sentences with the core action and use case front-loaded, followed by the cost warning, alternatives, and exclusions. Every sentence earns its place; no repetition of schema or annotation info.

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?

Although there is no output schema, the schema's maxResults ('Maximum referencing objects to return') and locationsPerObject ('call sites... per referencing object') already convey the result shape. The description covers purpose, usage timing, cost, alternatives, special label handling, and exclusions — an agent has everything needed to select and invoke it correctly.

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 baseline is 3. The description still adds meaning by broadening the name parameter domain beyond the schema's 'object or method name' to include fields and label IDs, and by documenting the label ID format expansion. maxResults and locationsPerObject are already well described by the schema.

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?

Opens with 'Full index scan for all usages of an object, method, field, or label ID' — a specific verb, resource, and scope. The label-ID and not-for-extensions clauses directly distinguish it from siblings find_callers and find_extensions, so an agent can disambiguate without opening schemas.

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?

Explicitly states the trigger ('Use for impact analysis before changing or deleting an object'), the cost-based alternative ('Prefer find_callers when XRef index is loaded (O(1))'), and a hard exclusion ('NOT for extensions only — use find_extensions for CoC/event handlers'). Nothing is left to inference.

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