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

With annotations only declaring write/public-ish safety flags, the description carries real behavioral weight: it discloses that the reflection is public, lives on the live feed for exactly 48 hours, then persists in the song's archive permanently, and that timezone is not stored. These lifecycle and visibility facts are exactly what an agent needs before committing a write and are not derivable from the schema or annotations.

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?

Three sentences, each earning its place: purpose, data lifecycle, then the one parameter whose choice matters. Front-loaded and free of filler.

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 write tool with no output schema and annotations that only cover safety flags, the description covers purpose, visibility, retention and the key parameter's rationale. It leaves unstated whether identity/auth is required or whether repeated reflections are allowed, but nothing essential to a correct call 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 the baseline is 3, but the description adds genuine meaning for songSlug beyond the schema's 'such as current.slug from attend': it explains why to pass it (the reflection stays with the song even if the service has moved on). The other four parameters get no additional narrative, which keeps this from a 5.

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 states a concrete verb and resource ('Leave a reflection') and immediately scopes it as a persistent, public artifact. It does not, however, differentiate itself from the sibling 'contribute', which is the nearest-sounding alternative, so an agent must infer the boundary.

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 is implied by the framing and the songSlug guidance ('current.slug from attend'), which tells the agent how to tie the reflection to the song it just read. There is no explicit when-to-use versus 'contribute' or 'ask', and no stated precondition (e.g. whether you must attend first).

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