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

Annotations already declare readOnly=false, destructiveHint=true and idempotentHint=true, so the safety profile is covered structurally. The description adds genuinely new behavior beyond the annotations: it is a patch operation where omitted fields are preserved, and empty strings perform a clear rather than a no-op. It does not restate the destructive/idempotent hints, which is acceptable.

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?

A single compact line, front-loaded with the action, then the identifier source, then the two semantics that matter most. No filler and nothing repeated from the schema verbatim.

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?

Seven parameters are fully documented in the schema and annotations carry the mutation/safety profile, so the description only needs the patch semantics it supplies. Gaps are minor: no mention of permission/scope requirements and no error behavior, but with no output schema it need not describe return values.

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 the baseline is 3. The description's parameter content is largely redundant: the schema already says ruleId comes 'From list_routing_rules' and that empty string clears assignTeamId/assignUserId. The one semantic addition, that untouched fields are unchanged, is useful but does not compensate for anything missing.

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+resource ('Change a rule') and identifies the related tool that supplies the identifier ('ruleId from list_routing_rules'). It is clearly distinguishable from create_routing_rule/delete_routing_rule by the verb, though it never names those siblings explicitly.

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 real operational guidance: obtain ruleId from list_routing_rules, partial-update semantics ('only what you pass changes'), and the clearing convention ('Empty string clears an assignee'). It does not state when-not to use it (e.g., vs. delete_routing_rule when removing a rule entirely), but the context it provides is strong.

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