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

Annotations already communicate that this is not read-only, is idempotent, and is not destructive. The description adds useful semantic context ('score impact') but does not disclose additional behavioral detail such as whether the value overwrites the existing weight or whether there are downstream effects on scoring.

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 concise sentences with the core action front-loaded and no filler. The pointer to the getter tool earns its place and does not bloat the description.

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 simple three-parameter mutation with annotations covering idempotency and non-destructiveness, the description is mostly complete. It tells the agent what to update and how to inspect current weights, which also helps discover valid signalType values. However, with no output schema and no explicit mention of the response or success behavior, it leaves a small gap.

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%, so the description must compensate, but it only explains the concept of 'weight' and does not clarify what values signalType accepts, how campaignId should be formatted, or how scoreImpact interacts with the range constraints already present in the schema. It adds some meaning but leaves key parameter semantics undocumented.

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 clearly states a specific action ('Update the weight') on a specific resource ('signal type for a campaign'), and clarifies that 'weight' means 'score impact.' This distinguishes it from the related getter, campaignstack_get_campaign_weights, and from the broader update_campaign 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 description explicitly directs the agent to use campaignstack_get_campaign_weights to see current weights before updating, which is practical and context-rich. It does not go further to state when not to use this tool or compare it to other update_* siblings, so it stops short of a 5.

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