messages_search

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

Annotations already establish readOnlyHint=true and destructiveHint=false, and the description adds genuinely new behavior: newest-first ordering, a hard Full Disk Access requirement with a typed error on failure, and an explicit 'sending isn't supported' limitation. It stops short of covering result caps or pagination, but the extension beyond annotations is substantial.

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?

Three short sentences, all front-loaded: scope and ordering first, then result-shape pointers, then the access prerequisite and the text-only constraint. No filler and nothing buried at the end.

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?

With annotations covering safety, an output schema covering return values, and the description covering the auth prerequisite, ordering, and capability limits, an agent has nearly everything needed to call it correctly. The only real omission is any guidance on the 'limit' parameter or result-size ceilings.

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 0%, so the description carries the burden. 'Search by text content' implies how 'query' is matched, but 'limit' is never mentioned in either the schema or the description, and the return pointer note (id/summary format) explains output rather than inputs.

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 and resource ('Search Messages by text content') plus the backing store (chat.db) and ordering (newest first). It implicitly separates itself from messages_chats and messages_with, but it never names those siblings outright, so an agent must infer the boundary rather than read it.

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 gives conditions ('Text-only for now; sending isn't supported') and a prerequisite (Full Disk Access), which frames when the tool is applicable. It does not, however, tell the agent when to pick this over messages_with or message_body for similar-looking lookups, leaving that comparison implied.

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