search_mentions

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

Annotations only declare readOnlyHint=true, and the description adds a genuinely non-obvious behavior: Reddit's search does not index comments, so results are posts only. This prevents the agent from expecting comment hits, which is valuable context beyond the annotation. It stops short of disclosing result ordering or rate-limit behavior, but the core behavioral caveat is covered.

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 sentence with the action front-loaded and zero filler; the parenthetical packs the search limitation and sibling routing into a compact aside. Every clause earns its place.

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 an output schema present and readOnlyHint=true, the safety and return-value burden is covered elsewhere. The description handles scope, content type, and sibling routing, leaving only the account parameter unexpained — a real but narrow gap for a 4-parameter 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 0%, so the description must carry the semantic load, but it only clarifies query (a 'username or keyword'). The account parameter is left unexpained and ambiguous — unclear whether it filters results, scopes to an account, or selects an authenticated identity — and limit/time_filter receive no added meaning beyond their self-evident schema types.

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 all of Reddit for a username or keyword' — with an explicit scope qualifier that distinguishes it from search_subreddit. The parenthetical narrows the resource to posts only and routes comment mentions to get_inbox, leaving no ambiguity about what this tool does.

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 parenthetical provides explicit routing: comment mentions 'arrive via get_inbox', telling the agent when not to use this tool and where to go instead. It implicitly contrasts with search_subreddit via 'all of Reddit', though it does not name that alternative explicitly or give selection conditions for the other companion tools.

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