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

Beyond the readOnlyHint annotation, the description reveals useful behavioral traits: parallel fan-out, RRF-based result merging, peer configuration via D365_FEDERATION_PEERS, and the local server always being the primary source. These details help the agent anticipate how the tool behaves and how it is configured.

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?

Four tight sentences, each earning its place: the core action, the target use case, the peer configuration mechanism, and the local-server inclusion. It is front-loaded with the most important information and contains no filler.

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?

The description together with the fully-documented schema gives an agent enough to invoke the tool correctly: query is required, topK defaults to 5, peerApiKeys are optional, and peers come from an env var. It doesn't describe the exact output shape or RRF details, but those are not strictly required for correct invocation.

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 the schema already documents all parameters (query, topK, peerApiKeys) including defaults and ordering semantics. The description adds little parameter-level detail beyond what the schema provides, so the baseline 3 is appropriate.

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: 'Fan-out search across multiple ALM XPP MCP server instances in parallel and merge results using Reciprocal Rank Fusion (RRF).' It clearly distinguishes this federated, multi-server tool from the many single-server search tools in the sibling list, such as search_d365_code or batch_search.

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?

The description states a clear use case: 'Useful when D365 code is split across multiple organisations or knowledge bases (e.g. one per client, one standard KB).' This gives the agent good context for when to invoke it, though it does not explicitly name alternatives or state when not to use it.

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