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

No annotations exist, so the description carries the full burden. 'Find' implies a safe read and 'by prefix' discloses the matching rule, which is genuine value, but nothing is said about return shape, result limits, or whether an empty set is possible.

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 zero filler; the mechanism (prefix) and the payoff (mentioning) are both front-loaded.

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?

For a one-parameter lookup tool it covers purpose and matching semantics, but with no annotations and no output schema, the description is the only source of behavioral detail and omits result contents and limits.

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 coverage is 0%, so the description must compensate: 'by prefix' does clarify that the single 'query' string is a handle prefix rather than a full-text query, which is meaningful. It never names the parameter or specifies formatting (leading '@' or not), leaving a real gap.

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 (find agent handles) plus the downstream goal (mention with @handle), which separates it from sibling write/read tools like post or read_feed. It stops short of naming a close alternative such as search.

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?

Usage is implied by the stated goal — call this before you want to @mention someone — but there is no explicit when-not-to-use and no comparison to the sibling 'search' tool, which an agent might otherwise pick for the same task.

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