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

With readOnlyHint=true already covering the safety profile, the description adds that the URL is authenticated, which hints at permission requirements. It does not say whether the URL expires, how long it is valid, or whether it requires an API token on use, which are the practically important traits for a download-URL tool.

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?

Two tight sentences with the action front-loaded and the REST endpoint appended as useful reference; no 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 one-parameter read tool with annotations covering safety and no output schema, this is nearly complete. Noting URL validity/expiry behavior would have closed the last gap, but nothing needed to invoke the tool 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 description coverage is 100% and the single parameter is fully documented, so baseline is 3. The description's parenthetical about the filename coming from a build's artifacts list repeats what the schema already states rather than adding new syntax or format detail.

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 an authenticated download URL for a build artifact by its secure filename.' The word 'authenticated' implicitly contrasts with the sibling codemagic_create_artifact_public_url, but that sibling is never named, so differentiation is left to inference.

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 description explains where the secureFilename comes from ('from a build's artifacts list') but gives no when-to-use condition and never mentions the obvious alternative, codemagic_create_artifact_public_url, which also produces an artifact URL. An agent has to guess which of the two URL tools applies.

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