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

Annotations already declare this is a non-read-only but non-destructive, closed-world mutation. The description adds real behavioral context beyond them: the effect is scoped to today only, calls are cumulative ('each call adds more'), there is a 500 cap, and the return value is the total extra granted today. It does not state auth/permission requirements, which keeps it short of a 5.

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?

Four tight sentences, front-loaded with the trigger condition and scope, then the alternative. No filler and nothing repeated from structured fields.

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 additive mutation with an output schema and full annotation coverage, the description covers trigger, scope, cumulative behavior, cap, return value, and the alternative tool. Nothing an agent needs to call 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 coverage is 100%, so baseline is 3. The description nonetheless reinforces the semantics an agent could misread from a default of null: omitting 'deck' boosts the account-wide allowance rather than a specific deck, and it restates the 500 ceiling on 'extra'.

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+resource ('adds extra new cards for today') with the exact scope (today only, per-deck or account-wide) and names the sibling it is not (set_limits). An agent can distinguish it from set_limits and create_cards without opening any 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?

Explicit trigger condition is given ('when the user wants more new cards today than the daily limit allows'), reinforced by a concrete user utterance example, plus an explicit alternative ('To change the limit for every day, use set_limits'). Both when-to-use and when-to-use-something-else are covered.

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