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

No annotations are supplied, so the description carries the full behavioral burden. It does disclose a real side effect beyond the schema — that adding a server 'starts its first scan' — which is valuable and non-obvious. It does not state what happens on duplicate adds, whether the scan is synchronous or how long it takes, or what permissions are required for this mutation.

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 short sentences, front-loaded with the action and the three input modes, closed by the exclusivity rule. No filler and nothing repeated from the schema field descriptions.

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 mutation tool with no annotations and no output schema, the description covers how to identify a server and that a scan is triggered, but omits return value (added server object, scan identifier), error/duplicate behavior, and the auth implications only partially covered by the organisation parameter text. An agent could call it but could not anticipate the response.

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 coverage is 100%, so the baseline would be 3, but the description adds meaning the schema does not: it declares that exactly one of endpoint/repo_url/registry_name must be supplied, whereas the schema lists all five as optional with an empty required array. It also ties repo_url to the stdio server type, a semantic link the schema only hints at.

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 names a specific verb and resource ('Adds an MCP server') and enumerates the three supported identification modes: endpoint URL, repository URL (explicitly flagged as a stdio server), and registry name. This is clearly distinct from read-side siblings such as list_mcp_servers and list_registry_entries, though it never names an alternative explicitly.

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?

'Pass one of the three' establishes mutual exclusivity, which is genuine usage guidance absent from the schema (required is empty). However, it gives no guidance on which of the three modes to prefer for a given situation, no prerequisites (auth, organisation scoping), and no when-not-to-use conditions such as an already-registered server.

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