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

Annotations already declare readOnlyHint=true and openWorldHint=false, but the description goes further by explaining the concrete side-effect-free guarantees: 'never creates a tracker and never triggers a new crawl.' It also discloses the 404 tracker_not_found behavior, which is important for agents handling missing-tracker cases. This is exactly the kind of behavioral context the dimension rewards.

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?

The description is three sentences with no filler. The first sentence states the core function and key differentiator, the second covers safety guarantees, and the third handles error behavior and alternatives. Every sentence earns its place, and the most decision-relevant content is front-loaded.

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 single-parameter read-only tool with an output schema and safety annotations, the description is complete. It covers the operation, queried resource scope, side effects, error response, and routing to alternatives. There is nothing an agent needs to call this tool correctly that is missing, and the presence of an output schema means return-value details need not be repeated.

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?

The schema already fully documents the single parameter with a type, minLength, and an example. The description adds the framing 'raw tracking number' and 'across trackers already on the account,' which slightly enriches the parameter's meaning, but it does not add substantially new information beyond the schema. With 100% schema coverage, 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?

The description states a specific verb and resource: 'Returns existing tracking results for a raw tracking number across trackers already on the account.' It also clarifies the key distinction that no trackerId is needed, and it distinguishes itself from siblings by naming search_tracking and track as alternatives. This gives an agent a clear, unambiguous understanding of what the tool does.

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 provides explicit when-to-use guidance: 'Use this first when a tracker may already exist.' It also gives a concrete fallback path on 404, directing the agent to search_tracking or track with selection criteria ('per-call' vs 'per-shipment'). This fully resolves the choice among the closely related sibling tools.

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