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

Annotations already cover safety (readOnlyHint=true, destructiveHint=false) and world scope, so the bar is lower. The description still adds genuine value by disclosing the returned metrics (count, total value) and that values are expressed in the account currency — information not available anywhere else since there is no output schema.

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 core output description front-loaded. The trailing 'GET /deals/stats' is low-value for an agent that never makes HTTP calls directly, but it is brief rather than bloated.

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 zero-required-parameter read tool with annotations and no output schema, the description supplies what is actually needed: what is measured, the currency semantics, and the optional filter. Only minor gaps remain, such as whether stats aggregate across pipelines or time periods.

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?

With 100% schema coverage the single parameter is already documented, so the baseline is 3. The description earns an extra point by stating the parameter is optional and defining the no-argument default (all deals), which the schema alone does not convey.

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 names a specific resource and output (number and total value of deals) plus an optional scope (tag-filtered), which cleanly separates it from list_deals/search_deals. It stops short of naming a sibling explicitly, so an agent must infer the boundary itself.

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?

'Number and total value of all deals' implies an aggregate-count use case, and the parenthetical clarifies when to pass a tag. However, there is no explicit guidance on when to pick this over list_deals or count_records, and no exclusions or prerequisites are stated.

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