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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered; the description adds real context beyond that — the deletion cascades to meanings and their practice progress, propagates "on every device", requires the words:delete permission, and is irreversible in this context. It doesn't address behavior for an unknown word_id, but the added behavioral disclosure is substantial.

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 short sentences, front-loaded with the action and its cascade, followed by the irreversibility warning and the permission requirement. No filler or restatement of the title beyond what the action sentence requires.

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 destructive one-parameter mutation with full annotation coverage and an output schema, the description supplies what matters: scope of deletion, device-wide propagation, irreversibility, and auth prerequisite. The only gap is error/not-found behavior, which is minor given the output schema.

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?

Single parameter with 100% schema coverage, and the schema already explains that word_id comes from another tool's result. The description adds no format or sourcing detail beyond the schema, so the baseline 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?

States a specific verb and resource ("Deletes one word from the user's notebook") and scopes the cascade ("with its meanings and their practice progress"), which implicitly separates it from remove_meaning. It stops short of naming an alternative sibling, so an agent comparing delete_word against remove_meaning or set_retired gets a hint rather than an explicit contrast.

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 irreversibility warning ("It cannot be undone here") and the permission requirement give useful preconditions for calling it, so usage is implied for genuinely unwanted words. However, it never states when to prefer remove_meaning or set_retired over deleting the whole word, and no exclusion criteria are given.

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