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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuine value beyond that by disclosing that answers are client-aware (ChatGPT, Claude, Cursor, Codex, plain MCP) and that the content spans rendering behaviour and access tiers. It stops short of saying whether the client is auto-detected or inferred from the topic argument.

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 'explains what the server can do' claim, and the enumerated facets are compressed into parallel clauses rather than prose sprawl. The client-name list is slightly heavy but each item carries information.

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 one optional parameter, no output schema and a read-only annotation set, the description gives enough to call it correctly and to know what kind of answer to expect. The only gap is how the two topic modes differ in depth, which the schema covers minimally but the description does not reinforce.

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% and the single 'topic' enum already documents both 'overview' and 'auth' with their meanings. The description never mentions the topic argument at all, so it adds no meaning beyond the schema; 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?

The description opens with a specific verb and resource: 'Explains what the FXMacroData MCP server can do', then enumerates the exact facets covered (which tools render MCP Apps, which return plain rows, public vs subscriber-only, per-client selection differences). No sibling tool in the list serves this self-documentation role, so the purpose is unambiguous against the catalogue.

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?

It gives three concrete triggering situations: questions about what is available, why visuals are not showing, and how to get the same result in another interface. That is clear when-to-use guidance, but it names no exclusions or alternative tools (e.g. data_catalogue for a pure listing), so an agent could still hesitate between this and the catalogue tools.

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