Set Login URIs

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

Annotations (readOnlyHint=false, destructiveHint=false) indicate a non-read, non-destructive write operation. The description adds value by explaining the behavior of 'replace' and 'merge' modes and the allowed match values, which goes beyond the annotations. However, it doesn't mention side effects like confirmation or permission requirements.

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?

The description consists of two concise sentences. The first sentence clearly states the function and the two modes, and the second lists the valid match values. No unnecessary words or repetition.

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?

The tool has no output schema, so the description should mention what the tool returns (e.g., success, updated item). It also lacks context about prerequisites (e.g., id must refer to an existing item) or error handling. The description is adequate for simple usage but incomplete for a mutation tool.

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 schema already documents all parameters. The description provides a brief translation: 'mode=replace overwrites the full list; mode=merge updates existing URIs and adds new ones by URI' and lists match values, but these add minimal meaning beyond the schema's own 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?

The description states 'Set or update the URI list on a login item', which is a specific verb and resource. It clearly differentiates from siblings like keychain_update_item by focusing solely on URIs, and the additional details on modes and match values reinforce its purpose.

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?

The description implies when to use the tool (for setting or updating URIs with two modes) but does not explicitly state when to prefer it over alternatives like keychain_create_login or keychain_update_item. No exclusions or 'when not to use' guidance is provided.

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