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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely new context: the catalog's size and category taxonomy, and the shape of each match (slug, description, parameters, quota-unit cost) — important since there is no output schema. It does not state ordering or relevance behavior, which keeps it off a 5.

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?

Three sentences, front-loaded with the purpose, then catalog scope, then return shape, then the next action. The category list is long but is load-bearing vocabulary rather than filler; nothing here is redundant with the schema or annotations.

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 read-only three-parameter search with no output schema, the description covers what it searches, how big the corpus is, what a result contains, what a call costs, and what to do with a hit. An agent has everything needed to invoke it correctly and act on the result.

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 coverage is 100%, so baseline is 3, but the description earns an extra point by enumerating the eleven category names, which expands the `category` parameter's usable vocabulary beyond the schema's three examples. `limit` and query syntax remain fully delegated to the schema, which 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 ("Find upAPI operations to call") and immediately scopes the corpus (128 operations across 11 categories). It also explicitly separates discovery from execution by pointing at `call_op`, so an agent can tell this apart from `call_op`, `web_search_post`, and `wikipedia_article_get` without opening a schema.

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?

Clear when-to-use framing: search the catalog first, then "Run one with `call_op`." It also documents the browse-everything escape hatch (empty query). It stops short of an explicit when-not clause, e.g. skipping search when the slug is already known, but the sequencing guidance covers the main decision.

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