Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add rules/atlanhq/agent-toolkit/tool-development-guidegit clone --depth 1 https://github.com/atlanhq/agent-toolkitWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.01138 | $0.01138 |
| Opus 5 | $0.00569 | $0.00569 |
| Sonnet 5 | $0.00228 | $0.00228 |
| Haiku 4.5 | $0.00114 | $0.00114 |
Grade A, and why
tool-development-guide scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 202 lines — stays where its author put it; the contents beside it link to each section on GitHub.
This guide outlines the core coding patterns for implementing tools in the Atlan MCP server.
Tool Implementation Pattern
- Define core function in tools.py
- Register function as MCP tool in server.py
- Use appropriate type hints for PyAtlan and MCP compatibility
Core Function Template (tools.py)
def implement_atlan_tool(
param1: str,
param2: Optional[int] = None,
param3: Optional[Dict[str, Any]] = None
) -> Any:
"""
Implement an Atlan tool with appropriate parameters.
"""
logger.info(f"Starting tool execution with parameters: param1={param1}")
try:
# Tool-specific implementation
result = execute_atlan_operation(param1, param2, param3)
logger.info(f"Tool execution completed successfully")
return result
except Exception as e:
logger.error(f"Error executing tool: {str(e)}")
logger.exception("Exception details:")
return get_appropriate_default_value()
MCP Tool Registration Template (server.py)
@mcp.tool()
def registered_tool_name(
param1: str,
param2: Optional[int] = None,
param3: Optional[Dict[str, Any]] = None
) -> Any:
"""
Tool description with clear purpose.
Args:
param1: First parameter description
param2: Second parameter description
param3: Third parameter description (complex structure)
Returns:
Description of return value
Example:
registered_tool_name("value1", 42, {"key": "value"})
"""
return implement_atlan_tool(param1, param2, param3)
Common Operation Patterns
Asset Search Operation
def search_operation(criteria):
search = FluentSearch()
# Add filters based on criteria
request = search.to_request()
results = list(atlan_client.asset.search(request).current_page())
return results
Asset Retrieval Operation
def get_asset_operation(qualified_name, asset_type):
try:
asset = asset_type.get_by_qualified_name(
qualified_name=qualified_name,
min_ext_info=True,
atlan_client=atlan_client
)
return asset
except Exception as e:
logger.error(f"Failed to get asset: {e}")
return None
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 202 lines · 1,138 tokens per session scan A 0db7ddd300d5
tool-development-guide is a cursor rule published in the GitHub repository atlanhq/agent-toolkit (32 stars, last pushed 4d ago), licensed MIT. It adds 1,138 tokens to every session, about $0.0057 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other cursor rules, from other repositories
api-property-optionality-hygiene
Fix ApiProperty/ApiPropertyOptional optionality mismatches in DTO files; use for scheduled batch fixes or DTO edits.
java-springboot-jpa-cursorrules-prompt-file
description: "Cursor rules for Java development with Springboot and JPA integration." globs: / alwaysApply: false.
conservative-file-creation
Check for existing files before creating. Be conservative about new files and code.
secure-dev-rust
These rules apply to all Rust code in the repository and aim to prevent common security risks through disciplined use of memory safety, input validation, error handling, and safe APIs.
design-patterns
Design patterns (GoF) and file size conventions for sweagent TypeScript codebase.
cursorrules
ALWAYS start your session by reading AGENTS.md and .memory/wiki/hot.md to get project context before suggesting code or answering questions.