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

Annotations already flag this as destructive and non-read-only; the description adds the operational context that matters: partial-update semantics, mandatory human approval, verbatim-text pass-through, and the warning that instructions fields must not be used as a proxy for real settings (SMS toggles, pace, transfers, blocklists). It does not describe what happens on validation failure, permission/auth requirements, or the response shape.

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?

Front-loaded correctly: the partial-update rule and the approval requirement come first, before the more granular instructions-field guidance. It is long (~300 words), but this is a destructive 40-parameter mutation tool where the length is defensible. Some sentences duplicate what the schema already says about outbound/incoming instruction routing, which is the main trimming opportunity.

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?

For a destructive tool with 40 required-but-nullable parameters and no output schema, the description covers the critical failure modes: sending the whole config, missing approval, paraphrasing user text, and abusing instruction fields as settings. What it omits is the return behavior and error handling, which would be more valuable given no output schema exists to fill that gap.

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 parameter mechanics are already documented; the description goes beyond that by explaining the semantic split between `instructions` (outbound-only) and `incomingCallInstructions` (incoming-only), and that `incomingSmsInstructions` is an overlay rather than the SMS on/off switch. It also pre-empts the common misuse of stuffing generic assistant rules into instruction fields. A 4 rather than 5 because these rules are partially restated rather than adding new per-parameter detail.

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 a specific verb+resource: 'Update one SkipCalls receptionist's configuration.' An agent immediately knows this is a partial-mutation tool on a single agent record. It does not name or differentiate itself from the other update-shaped siblings (updateOutbound, updateTimezone, onboarding_create_receptionist), so it stops short of a 5.

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?

Gives explicit pre-conditions ('ALWAYS get explicit user approval before calling; summarize the proposed change in plain language and wait for confirmation') and an explicit invocation rule ('Send ONLY the fields you intend to change — never the whole config'). It also tells the agent when to stop and ask the user for more input rather than proceeding with generic instructions. No sibling alternative is named, which keeps it out of 5 territory.

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