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

Annotations already declare readOnlyHint=true, so no safety disclaimer is needed here. The description adds useful scoping context ('only external...') and an explicit exclusion of API Store coverage, but it does not disclose response shape, pagination, or error behavior. This is comparable to a safe read-only search tool where the core behavioral requirement is already annotated.

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, no filler, with the scope constraint front-loaded before the routing guidance. Every sentence earns its place and the alternative tool is introduced efficiently.

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 simple read-only search tool with no output schema, the description covers scope, limitation, and routing to the correct alternative. It is slightly incomplete on query/limit semantics, but the parameter names and the tool title make those reasonably self-evident, and annotations cover the safety profile.

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%, and the description adds no meaning for 'query' or 'limit' beyond what their names imply. Unlike the covered 'response_version', the two main operational parameters are left undocumented in both the schema and the description, so the description 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?

The description states a specific verb ('Search'), a precise resource ('external MCP servers registered in Siglume MCP Router'), and explicitly contrasts itself with siglume_search for broader discovery. This clearly differentiates it from its sibling and from the alternative search tool.

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 an explicit scope limitation ('only external MCP servers registered in Siglume MCP Router') and names the alternative for broader discovery ('use siglume_search'). This tells an agent exactly when this tool is appropriate and when another tool should be selected.

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