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

Annotations only supply destructiveHint=true, so the description adds useful behavioral color by disclosing that the resulting URL is public and time-limited. It stops short of stating the security implication (the artifact becomes accessible to anyone holding the link) or what happens at expiry, which is the key thing an agent should surface for a destructive-hinted 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, front-loaded with the action and scope, with no filler. The trailing REST endpoint line is mildly redundant with the name but genuinely useful for API-mapping agents, so it still earns its place.

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?

Two required, fully-described parameters, no nesting, no enums, and the operation is simple enough that the description plus schema is nearly sufficient. With no output schema, it would ideally state that the return value is the URL string, but that omission is minor.

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 both secureFilename and expiresAt (UNIX seconds) are already fully documented in the schema. The description mentions the secure filename concept but adds no format or constraint detail beyond it, so the baseline of 3 is appropriate.

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 ('Create a public ... download URL for a build artifact') and even names the API endpoint, so the action is unambiguous. However, it never distinguishes itself from the near-identical sibling codemagic_get_artifact_download_url, which is the one case where an agent could easily pick the wrong tool.

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 parenthetical '(shareable, time-limited)' implies the use case of generating a link to hand to a third party, so usage is inferable. But there is no explicit when-to-use or when-not-to-use guidance and no mention of the sibling that returns a non-public download URL, leaving the routing decision to inference.

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