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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety bar is lower. The description adds real context beyond that: it does not trigger discovery (no side effects/rate-limit cost) and it names the return shape, which matters 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 short sentences, each earning its place, with the core behavior and return fields front-loaded before the prerequisite. No filler or restated title.

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 one-parameter, non-nested read tool with no output schema, the description covers behavior, prerequisite, and the returned fields. Minor gap: no mention of ordering, pagination, or what an empty result looks like.

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?

Only one parameter (brandId) and schema coverage is 100%, with the schema already stating it comes from list_brands. The description's 'this brand's' adds no syntax or format detail beyond the schema, 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 (Lists) and resource (this brand's current competitor set), and even enumerates the returned fields (name, handles, score). The clause 'without re-running discovery' cleanly separates it from the sibling discover_competitors.

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?

Gives a concrete prerequisite: call discover_competitors first if none exist yet, which tells the agent when this tool will return nothing useful. It lacks a general 'prefer X over Y' rule, but the empty-state routing is explicit and actionable.

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