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

The description explicitly labels the action as 'persist' (write), consistent with annotations (readOnlyHint=false). It adds behavioral context about leaderboard/streak impact, which annotations do not provide. No contradictions.

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 sentences, each adding value: action, behavioral impact, prerequisite. No wasted words. Front-loaded with the primary purpose.

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?

The description covers key aspects (leaderboard, sign-in) but omits details on parameter selection (word vs. card_id), success feedback, and error cases. With 7 parameters and no output schema, more guidance is needed for a complete understanding.

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 57%, leaving three parameters (is_correct, selected_answer, time_taken_seconds) without schema descriptions. The description only clarifies is_correct via 'correct/incorrect', but fails to explain selected_answer or time_taken_seconds, which an agent needs for correct invocation.

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?

The description uses a specific verb ('Persist') and resource ('single word answer to mastery progress'), clearly distinguishing it from sibling tools like mark_word_known (which marks known state) or mark_word_difficult (difficulty level). The mention of mirroring web app scaling adds specificity.

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 states 'Requires sign-in' as a prerequisite but provides no explicit when-to-use or when-not-to-use guidance relative to alternatives such as mark_word_known or get_flashcards. An agent is left to infer context from the action verb.

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