add_instrument

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

With no annotations at all, the description carries the full disclosure burden. 'Give ... an extra instrument' implies a mutation, but nothing is said about whether the change is immediate/persistent, how to undo it, whether duplicates are rejected, or whether a score must be open/active first. Only the musical meaning of 'doubling' is added.

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?

A single sentence that is front-loaded with the action and keeps the qualifier in a tight parenthetical. It is dense but not padded; the nested parenthetical slightly hurts scannability but no wording 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?

For a two-required-parameter mutation tool with no annotations and no output schema, the definition is thin. It never specifies the accepted instrument string format, what the tool returns or signals on success, or how it behaves for a player that already has that instrument — all things an agent needs before calling it.

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, and it does fully explain player_id as an index into get_score_overview players. However, 'instrument' is left with no format guidance — no enum values, no reference to describe_enums, no case/accepted-name convention — so half the parameters remain ambiguous.

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 ('Give an existing player ... an extra instrument') and clarifies the musical concept with '(doubling)', which an agent could not infer from the name alone. It implicitly separates itself from add_player by requiring an *existing* player, though it never names that sibling.

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 parenthetical '(index in get_score_overview players)' tells the agent where the player_id value comes from, which is real prerequisite guidance. It gives no when-not guidance, no mention of the inverse remove_instrument sibling, and no indication of error conditions such as a player that already holds the instrument.

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