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

Annotations already declare write/destructive, so restating 'Write, destructive' adds little. The description does add genuinely new behavioral facts the annotations cannot convey: a null deckNote clears it, and the operation does not move dueAt, which bounds the blast radius. Return behavior and error semantics remain unstated.

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 short sentences, front-loaded with the mutation character and then the field list, with no filler. The opening 'Write, destructive' partially duplicates the annotations, which is the only wasted token.

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 five-parameter mutation tool with no output schema and zero schema description coverage, the description covers the essential contract: at least one field required, null semantics, and an unaffected field (dueAt). It omits the response shape and whether unknown/immutable fields error out.

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 0%, so the description must carry parameter meaning, and it names four of the five fields. Critically it supplies a semantic the schema cannot express: passing null for deckNote clears it (the schema types deckNote as a plain string with no nullable signal). deckId's role is left implicit, and no format or range guidance is given.

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 ('Update deck' implied by updateDeck) and enumerates the mutable fields: name, description, deckNote, newCardsPerDay. It does not explicitly differentiate from the overlapping sibling setDeckNote or updateCard, which also touch deckNote/card fields, so it stops short of a 5.

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?

'Send at least one.' gives a real precondition, which is more than most definitions offer. However, it never says when to use updateDeck versus setDeckNote (which covers one of the same fields) or updateCard, leaving the alternative-routing decision to inference.

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