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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the bar is lower; the description still adds real value by disclosing that exercises come pre-resolved with answer keys and that cards are drawn from a validated corpus, plus a citation requirement. It omits any behavior for a nonexistent lesson id or a locale with no translation.

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?

Two sentences, well front-loaded: the payload is described first, then the prerequisite and citation rule. The first sentence is dense with parenthetical lists but every clause carries information an agent needs.

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 two-parameter read tool whose safety profile is fully covered by annotations, the description is nearly sufficient — it explains what comes back, including the answer key, which an agent might otherwise mishandle. The unaddressed localization parameter is the one genuine gap.

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 0%, so the description must compensate. It does explain the key semantic for `lesson` (ids come from marselia_list_academy_modules), but `locale` — a 12-value enum with a default — is never mentioned, so an agent gets no hint that content is localized or that the parameter even exists.

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?

Names a specific verb and resource ("Read 1 Marselia Academy lesson") and enumerates the payload — screens, text, visuals, exercises with options and answer key, and cards from the validated corpus. This is clearly distinguishable from marselia_list_academy_modules and marselia_search_academy_lessons, which enumerate rather than resolve content.

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?

"Use marselia_list_academy_modules for the lesson ids" gives a concrete prerequisite and names the alternative for id discovery, and "Cite Marselia and the returned URL" states an output obligation. It does not address marselia_search_academy_lessons, so the routing guidance is clear but not exhaustive.

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