now_playing_history

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It does disclose that the tool is read-only and that it consumes 2 reads ('🟡 (2 reads)'), which is genuinely useful cost and side-effect information beyond what the schema offers. It does not describe edge cases (e.g., empty history or nothing currently playing), but the core safety profile is transparent.

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 tight sentence front-loads the essential function, then appends the cost indicator and read-only note. Every element earns its place and there is zero filler or redundancy.

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 read-only tool with three fully documented optional parameters and no output schema, the description covers the core behavior, dedupe semantics, cost, and side-effect profile. Output shape is handled by the response_format parameter. The only notable gaps are the absence of explicit sibling routing and edge-case behavior, which are minor for this tool's complexity.

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 100%, so the schema already documents all three parameters (limit, dedupe, response_format) with defaults and meanings. The tool description itself adds no parameter-level detail beyond the schema, which lands it at the baseline of 3.

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?

The description clearly states what the tool does: it merges recently-played items with the currently-playing item, deduped, with the current item on top. The merge behavior ('recently-played plus currently-playing') implicitly distinguishes it from siblings like get_recently_played and get_currently_playing, though it never names those alternatives explicitly.

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?

Usage context is implied rather than stated: the 'merged listening stream' phrasing suggests this is the tool to use when a combined view of recent and current playback is needed, versus a sibling that returns only one of the two. However, there is no explicit when-to-use/when-not-to-use guidance or named alternative, so an agent must infer the routing decision.

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