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

Annotations already flag destructiveHint=true and idempotentHint=true, but the description adds genuinely useful mechanics: only passed fields change, null clears a value, and tags/custom fields wholesale replace existing values. That replacement warning is exactly the destructive behavior an agent must know before calling; only auth/rate-limit context is missing.

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?

One compact sentence with the operation class, target, lookup key, three behavioral rules, and the HTTP route — no filler and all critical constraints front-loaded.

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?

Given 13 parameters, a nested address object, and no output schema, the description covers the essentials: identification, partial semantics, null-clearing, replacement of collections, and the endpoint. The only omission is what the call returns (updated company vs. acknowledgement), which an agent might want to confirm the update.

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 baseline is 3, but the description adds semantics beyond the schema: partial-update behavior for the whole payload and the fact that custom fields (whose schema description only covers key/value typing) are replaced rather than merged. The 13-parameter surface is otherwise handled by per-field schema descriptions.

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?

States a specific verb ('update fields'), resource ('existing CRM company'), and lookup key (UID or name), immediately distinguishing it from create_company and get_company siblings. The 'WRITE:' prefix signals the operation class up front.

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 'update fields of an existing CRM company' plus the lookup semantics, so an agent knows to reach for it when the record already exists. However, it never names alternatives (create_company for new records, get_company_fields for discovering custom-field UIDs) or states prerequisites, leaving routing to inference.

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