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

Annotations already declare readOnlyHint=true, so the safety profile is covered, and the description still adds behavior beyond that: it says results include facts plus source snippets and that an empty result is possible. It stops short of describing ranking, result limits, or query-matching semantics, which would matter for a search tool.

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 sentences, each doing distinct work: purpose, when to use, and what comes back. The alternative tool is routed at the end of the usage sentence where it is most needed, and there is 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?

There is no output schema, and the description compensates by stating the return shape (facts and source snippets) and the empty case. Combined with the read-only annotation and a fully documented single parameter, nothing an agent needs to call this correctly is missing.

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?

Only one parameter, and the schema already documents it at 100% coverage ('What to look up, in natural language'). The description reinforces the natural-language framing but adds no syntax, phrasing, or length guidance beyond the schema, so this lands at the baseline.

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 ('Search') and a precise resource ('the user's long-term memory') and enumerates the target content ('fact, decision, project detail, or past statement'). It also makes clear what it is not by naming the sibling tool `briefing`, so an agent can distinguish the two without opening schemas.

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 an explicit trigger ('Useful before answering anything that depends on something particular the user told you earlier') and an explicit exclusion with the alternative to use instead ('For where things stand or what is in progress, call `briefing` instead'). The selection rule between this and the closest sibling is fully specified.

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