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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds scope context — that results span apps, wallets, exchanges, banks, infrastructure and partners, each tagged with a status — but says nothing about result volume, pagination, or how the directory is kept current.

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 short sentences, front-loaded with what the tool returns, then usage, then exclusion. The trailing 'Not for token prices' exclusion is somewhat wasted since no token-price sibling exists, but overall the text is tight.

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?

No output schema exists, but the description adequately conveys the return shape (projects with category and status). For a zero-required-parameter read tool whose safety traits are already annotated, the remaining gap is minor: no hint about result size or paging.

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 only 33%: 'q' is described as 'Name contains' while status and category rely purely on their enums. The description never mentions that these filters exist or how they interact (e.g., whether filters combine with AND), so it does not compensate for the coverage gap.

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 concrete resource — the Arc ecosystem directory — and enumerates the entity types and status values it covers, so an agent knows exactly what it retrieves. It does not differentiate itself from close siblings like arc_apps or arc_entity, which also appear to return project-level data.

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 explicit triggering questions (what exists on Arc, which projects are in a category, whether a company is on Arc) and one exclusion (token prices). However, it never names the alternative sibling tools to use instead for those adjacent questions, so routing between arc_apps, arc_entity, and this directory is left to inference.

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