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

Adds substantial context beyond the annotations: output links expire after 1 hour, the server downloads from download_url and stages it in R2 for the job duration, processing runs in a headless browser, and the input is deleted when the job ends. This gives the agent a full picture of lifecycle, retention and latency behavior.

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-loads the purpose in the first clause, then layers input requirements, options, return behavior and infrastructure notes. Sentences are information-dense and mostly earn their place, though the Cloudflare/headless-browser detail is longer than an agent strictly needs.

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 4-parameter tool with a nested generic settings object and no output schema, the description covers input shape, ordering, options, return format and expiry, and processing side effects. Nothing an agent needs to invoke it correctly 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 real value: it clarifies that the generic `settings` object carries `gapSec` for set_join_gap, that file order is meaningful, and that outputFormat/bitrateKbps apply 'where the tool supports them'. It notes 'two or more files' although the schema allows minItems 1, a minor discrepancy.

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 (joins) and resource (several audio files) plus the key constraint that order matters and a gap is optional. It clearly reads as a concatenation tool, but it never distinguishes itself from the closest sibling, crossfade_joiner, so an agent must infer the boundary between the two.

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?

Gives operational prerequisites (two or more files, each with a public HTTPS download_url, in processing order) which implies the use context, but offers no explicit when-to-use, when-not-to-use, or alternative routing such as crossfade_joiner for overlapping transitions.

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