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

The annotations already declare readOnly=false, idempotent=true, destructive=false, so the safety profile is covered; the description should add context about what happens to data or what constraints apply. Instead, its 'retain for at least 4,200 seconds' statement conflicts with the schema's retention_seconds minimum of 60, which actively misleads an agent configuring a short-lived shard. The encryption claim is also unexplained (at-rest? in transit? returned key?).

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?

A single compact sentence with the scope constraint front-loaded and no filler. It is efficient, though efficiency here reflects under-specification rather than disciplined editing.

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?

A write tool with no output schema, 0% parameter coverage, and no annotation coverage of encryption or payload handling means the description carries the full burden, and it does not meet it. It omits payload size/format expectations, the shard-count limit's practical meaning, and the relationship between the stated retention floor and the schema's actual bounds.

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 0% and none of the three parameters are named or explained: the 5,000,000-char data payload, the csv/json format switch, and the 60-86400 retention range with a default of 86400. The one parameter the description does touch, retention, is described with a value (4,200s) that contradicts the schema's stated minimum.

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 specific verb and resource ('Encrypt one of up to 64 private feature shards') with useful scope information about campaigns. However, it never reconciles the 'encrypt' framing with the tool name 'upload_campaign_shard', so an agent cannot tell whether the tool stores bytes, encrypts them, or both, and it never contrasts with the sibling upload_private_dataset.

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 gives operational constraints (up to 64 shards, large campaigns), but no explicit when-to-use/when-not guidance and no pointer to alternatives such as upload_private_dataset or upload_repair_matrix, which sit right next to it. The agent must infer selection from the tool name alone.

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