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

Goes well beyond the annotations: it discloses asynchronous side effects (a fresh volume/difficulty/coverage lookup is queued, keywords show 'researching' for a few minutes), partial-success handling ('notArchived ... left alone'), and the zero-cost trait. Annotations only give the safety profile (non-readonly, non-destructive, non-idempotent); the description supplies the operational behavior an agent needs.

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 tightly packed sentences, front-loaded with the core action, then side effects, then the disambiguation. Every clause earns its place with 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?

For a 2-parameter mutation tool with no output schema, the description covers the action, its async consequences, the partial-failure return field (notArchived), cost, and sibling disambiguation. Nothing an agent needs to invoke it 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?

Schema description coverage is 100%, so both parameters (site, keywords) are already documented, including the case-insensitive matching note. The description adds the ordering nuance ('onto the end of the list') but no syntax or format detail beyond the schema, so the baseline of 3 applies.

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 (moves/restores) plus resource (archived keywords), and it names the exact source list (list_archived_keywords) and destination (list_my_keywords). It also explicitly distinguishes itself from the similarly-named restore_keyword sibling, so an agent can disambiguate without opening either schema.

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 routes the agent clearly by naming restore_keyword as the wrong choice ('lifts an exclusion') and pointing at list_archived_keywords as the source. It adds a useful 'Free' cost note. It stops short of stating explicit preconditions (e.g., what happens if the keyword is already on the list), so it's strong but not fully prescriptive.

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