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

Annotations already declare destructive/idempotent/non-read-only, and the description adds value on top: a required human-approval step and a non-obvious side effect (pausing preserves setup instead of removing the number). However, "Send only changed fields" sits in tension with a schema that marks all 9 parameters required, which leaves the actual mutation semantics slightly ambiguous.

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-loads the identity of the operation and the key parameter in the first clause, then packs field semantics and the approval requirement into dense, non-redundant sentences. 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?

For a 9-required-parameter destructive mutation with no output schema, the description covers approval and pause/schedule side effects well but leaves a real ambiguity unresolved: whether the agent must supply all 9 fields or only changed ones. It also says nothing about what a successful update returns or how failures surface.

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 baseline is 3. The description restates semantics already present in the schema (clearWorkHours=true means 24/7; isActive=false keeps configuration), adding little beyond the parameter docs, and its partial-update instruction conflicts with the schema's required list.

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+key: "Change one transfer number by transferShortId." It then enumerates the exact mutable facets (label, description, phone, schedule, mode, isActive), which separates it cleanly from transfer_numbers_add, transfer_numbers_delete, transfer_numbers_reorder, and transfer_numbers_list.

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 clear operational context: use isActive=false to pause rather than delete, use clearWorkHours=true for 24/7, and send only changed fields. It also mandates approval before calling. It does not explicitly name a sibling alternative or exclusion, so it stops short of a 5.

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