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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds real behavioral detail beyond them: the prefix-matching rule ('each query word must start a word in the puzzle'), the contents of each hit (PDF, play URL, slugs), and the answer-key caveat for puzzle vs game/drawing PDFs. It does not mention pagination or result limits.

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?

Five sentences, all substantive and front-loaded: matching semantics first, then filters, then return contents, then the answer-key caveat. The 'like the site's search box' analogy is compact and useful; the only minor cost is density, but nothing is wasted.

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?

Even though an output schema exists, the description explains what hits contain (PDF, play URL, slugs) and which sibling tools to chain into, plus the edge case that non-puzzle PDFs lack answer keys. Combined with full schema coverage and annotations, an agent has everything needed to call and use this tool.

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% with enum values documented, so the baseline is 3. The description still adds meaning the schema lacks: how the query string is matched (word-prefix matching with the 'ant' vs 'Elephant' example) and that activity/level act as narrowing filters rather than required inputs.

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 (search) and resource (activities) with explicit scope: title, topic, or a word inside the puzzle. It even names the downstream siblings (get_activity, show_word_search) that consume the returned slugs, so an agent can tell what this tool is for versus browsing or fetching tools.

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?

Gives clear usage context: 'Narrow by activity or level if you like' explains the optional filters, and the mention of slugs for get_activity and show_word_search implies the chaining workflow. It stops short of naming alternatives such as list_activities or stating when browsing beats searching.

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