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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds real value beyond that: no pagination (whole set in one page), plan-based slot ceilings (Free 1, Creator 3, Pro 5, Business 10), and the fact that last_snapshot_date is null until the first refresh.

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?

Five short sentences, front-loaded with the purpose and payload, then plan limits, then the no-pagination and null-date caveats. No sentence is filler; the plan-tier list is dense but earns its space by telling the agent what the slot numbers mean.

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 zero parameters, rich annotations, and no output schema, the description covers enough to call it correctly: what is returned, that it is unpaginated, and a null-value edge case. It stops short of describing the per-entry shape beyond "numbers from its latest snapshot," which leaves some return-format ambiguity against the absence of an output schema.

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 tool takes zero parameters, so the baseline of 4 applies. There is nothing in the input schema for the description to clarify or contradict.

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 ("List tracked competitors") and immediately scopes the payload: every tracked account, its latest snapshot numbers, and plan slot counts. This is clearly distinguishable from get_competitor (single account), add_competitor, and remove_competitor.

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?

Usage is implied by the return description – an agent can infer this is the discovery/enumeration call before drilling into get_competitor – and "Whole set in one page" signals no pagination loop is needed. However, there is no explicit when-to-use or when-not-to-use statement, and no named alternative.

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