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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered; the description adds real value beyond them by enumerating the return payload (hub fields, deduped player list, market_news with narrative/topics/momentum/sources) and disclosing the negative case { covered: false } for untracked markets. It does not discuss data freshness beyond 'latest weekly' or any rate/coverage limits, keeping it short of 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?

Front-loaded with the trigger condition and return contents, but the 'whole-category map, not a self-selected competitor set' idea is stated twice in near-identical wording ('every player in it, not just a self-selected competitor set' and again later), which is pure redundancy in an otherwise compact paragraph.

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?

With no output schema, the description carries the return-value burden and does so fully: hub contents, deduped player fields, the market_news structure, and the not-covered sentinel. Combined with the discovery pointer to list_markets, an agent has everything needed to call and interpret it.

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% and the schema already specifies slug-exact vs name-ILIKE matching with an example. The description only restates 'a vertical slug or name'; its useful addition (pointing to list_markets for slugs) is routing guidance rather than parameter semantics, so the baseline 3 applies.

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 ('returns the published category overview plus every player') and explicitly distinguishes itself from the sibling family by contrasting the whole-category map with 'a self-selected competitor set' (i.e., find_competitors). An agent can route to it without opening the 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?

'Use when the user wants an overview of a whole market/category' gives an explicit trigger, and 'Use list_markets to discover slugs' routes to the prerequisite tool. It stops short of naming find_competitors or get_comparison as the alternatives for narrower questions, so the exclusion is implied rather than stated.

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