add_custom_directory

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

With no annotations present the description carries the full burden, and it does meaningful work: it discloses persistence location (~/.backlink-mcp/custom.json), that the entry survives updates, and the conditional visibility rule for location (only shown for projects in that area). It omits whether duplicate URLs are rejected, validation rules on url, and the effect of priority.

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?

Front-loaded with the action and its consequence, then parameter guidance in priority order. Dense but every clause carries information; the parenthetical file path and data.py reference are slightly internal-facing noise but still orienting.

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 7-parameter mutation with no annotations and no output schema, the description covers the high-value fields and persistence behavior but leaves priority, notes, URL format and duplicate handling undefined, so an agent could still call it incorrectly or redundantly.

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 0% across 7 parameters, so the description must compensate and it partially does: tags gets an example and a pointer to NICHE_TAGS, region gets accepted formats (global, country name/code, EU/GCC/ANZ/NA/SEA), and location gets conditional-display semantics. name, url, notes and priority are left fully unexplained.

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?

States a specific verb and resource ('Add your own directory/citation site') plus the downstream effect ('so find_opportunities includes it from now on'), which distinguishes it from sibling registration tools like add_custom_footprint. An agent knows exactly what this mutates and what it changes in later calls.

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?

Implies clearly when to use it: when the user has a directory/citation site not already in the built-in set and wants it surfaced by find_opportunities. It does not address when-not-to-use (e.g. duplicates already in the catalog, or the distinction from add_custom_footprint), so no explicit alternative routing.

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