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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so safety is covered. The description adds genuinely non-obvious behavior: deterministic lookup from the published command tree, no LLM or search, found=false with suggestions for nonexistent commands, deprecated commands returning deprecation notes and replacements even when hidden, and unknown versions returning the published version list.

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?

Front-loaded with the verb and the return payload; the routing rule lands last, which is defensible. Some mild over-elaboration (the parenthetical about the command tree and the redundant 'no LLM or search is involved'), but nearly every clause carries real information for the caller.

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?

An output schema exists so return values need not be described, yet the description still sketches them. For a read-only lookup tool with full annotation coverage, full schema coverage, and an output schema, nothing an agent needs to call it correctly or interpret a negative result 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?

Schema coverage is 100%, so the baseline is 3. The description still adds meaning beyond the schema: the name may omit the leading 'rpk', may use aliases at any level, or may be the page name ('rpk-topic-create') — forms the schema's single example ('rpk topic create') does not convey. It does not elaborate on context/session_goal, but those are self-documenting.

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?

Specific verb and resource ('look up one rpk CLI command by its full name') with an explicit enumeration of what comes back: usage, help text, flags with types and defaults, aliases, subcommands, scoping, plugin/release, docs URL. It is clearly distinguished from the sibling list_rpk_commands (singular lookup vs listing) and from ask_redpanda_question.

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?

Explicit routing rule: 'Use this before ask_redpanda_question for any question about a specific rpk command's flags, defaults, or existence in a release.' It also states acceptable input forms and the failure mode (found=false with close-name suggestions), leaving little to inference.

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