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

Beyond the annotations (readOnly=false, destructive=false, idempotent=true), the description discloses the partial-update semantics, that 'tools' is a full replacement of the existing list, that empty strings clear fields, that saving is atomic ('Saves at once'), that directories lag until sync/submit, that version/packages/repo are GitHub-sourced and non-editable, and that a paid credit is required. Nothing contradicts the annotations and the extra behavioral detail is substantial.

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?

Purpose is front-loaded in the first clause, then behavior, then the field reference. Every sentence carries information, though the inline field list partially restates schema descriptions, making it slightly long for a reference block.

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 an 8-parameter mutation tool with 1 required param, no output schema, and no nested objects, the description covers replacement semantics, clearing behavior, the required server identifier, syncing caveats, and prerequisites - everything an agent needs to call it correctly without opening the schema.

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?

With 100% schema coverage the baseline is 3, but the description adds rationale and consolidation beyond the schema, e.g. short_description's 100-char limit exists 'because the official MCP Registry rejects longer' and the tools field 'replaces the old list'. Some field limits duplicate the schema, but the added reasoning and the single-pass field summary lift it above baseline.

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 opening line states a specific verb and resource ('Edit the listing ManyCP sends to every directory') and even names the aggregation scope, so the agent knows exactly what is mutated. It further distinguishes itself from siblings by referencing the 'next sync or submit', which routes to sync_server/submit_server rather than update_listing.

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 clear operating context: 'Send only the fields you want to change; the rest stay as they are' and 'Directories that already list the server keep their current text until the next sync or submit.' It also states prerequisites ('Needs a launch credit, Starter or Pro'). It stops short of explicitly saying when to use add_server vs update_listing vs submit_server, so it is strong context rather than full alternative routing.

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