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

Annotations cover the read-only safety profile, and the description layers on substantial non-obvious behavior: credit cost and the 3-of-6-source charging threshold, EU/UK-only Meta ads, reviews stripped of author names, and drafts written for the client that never mention the competitor. This is behavior an agent cannot get from the annotations or 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 sentences, front-loaded with the core purpose and ending with the most decision-relevant facts (cost rule, read-only). The middle enumeration is long but each item is a distinct data source that earns its place, so it stays efficient without waste.

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 correctly closes that gap by stating what comes back ('the findings plus a shareable report URL'). Combined with the cost rule and read-only note, an agent has everything needed to decide and call correctly.

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 description coverage is 100%, so every parameter is already documented, establishing a 3 baseline. The description's detail (EU/UK Meta scope, client-oriented drafts) largely restates what the schema already says for country and client_domain, so it adds little beyond the structured fields.

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 ('One competitor in one call') and enumerates the concrete outputs (keywords, Meta/Google ads, SERP, review themes, landing page, backlinks, drafts, summary). This clearly distinguishes it from the many single-source siblings like competitor_ads_meta or keywords_for_domain.

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 context is clear: all-in-one per-competitor research with a stated billing rule ('20 credits, charged only when at least 3 of the 6 data sources answer') that helps an agent judge cost. It does not, however, explicitly tell the agent when to prefer the narrower siblings instead, so it stops short of 5.

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