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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is met; the description goes further by disclosing the 'Track not found' error behavior and warning that results are user-generated content to be treated as untrusted. That trust/error context is genuinely additive.

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?

Front-loaded with the purpose, then ID provenance, then error/trust caveats. The nine-field enumeration is long but earns its place since there is no output schema. Slightly dense but no wasted sentences.

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?

With no output schema, the field list substitutes for return-value docs, and the description also covers the missing-record case and the untrusted-content caveat. Nothing an agent needs to call this getter correctly is absent.

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% and the single param is self-documenting, so the baseline is 3. The description adds value by tying the pk to its provenance (search_tracks / get_top_tracks), which the schema does not convey.

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 ('Get one Instagram music track by its ID (pk)') and enumerates exactly which fields come back. An agent can distinguish this single-track lookup from list/search siblings at a glance.

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 it for a pk from `search_tracks` or `get_top_tracks`' gives an explicit precondition and names the tools that supply the required ID, which is exactly the routing info an agent needs. It stops short of stating when not to use it (e.g., bulk retrieval), so not a full 5.

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