Fetch a URL and measure time-to-first-byte, total fetch time, and response size. Flags missing compression, missing Cache-Control, oversized payloads, and slow TTFB.
| Name | Required | Description | Default |
|---|---|---|---|
| url | Yes | The URL to measure |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description is the sole behavioral disclosure. It clearly states that the tool issues a fetch to the target URL and produces diagnostic flags about compression, Cache-Control, payload size, and TTFB, which is meaningful beyond the schema. It does not cover edge behaviors such as redirects or timeouts, but the core operation is transparent.
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?
The description is two tight clauses that front-load the action and then list the diagnostic checks, with no filler or repetition. Every phrase carries information.
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 one-parameter, low-complexity tool, the description covers input, measured outputs, and flag categories. It omits concrete thresholds such as what counts as 'slow TTFB' or 'oversized', but an agent can still select and invoke it correctly.
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?
The schema already documents the single url parameter at 100% coverage. The description reinforces that the URL is what gets measured but adds no new parameter-level details, so the baseline score of 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 names a concrete verb ('Fetch'), a resource ('a URL'), and the exact measurements/findings (TTFB, total fetch time, response size, compression/Cache-Control flags). These specifics distinguish it from browser-oriented siblings such as pagespeed_insights without needing to open the schema.
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 implies the tool is for low-level HTTP performance triage by listing what it flags, but it never names alternatives or explains when not to use it. An agent must infer the use case from the metric names rather than receive explicit routing guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Many tools audit overlapping site signals (seo_audit vs structured_data_extract vs tech_stack_fingerprint; page_performance_check vs pagespeed_insights; ssl_cert_check vs ssl_labs_grade; broken_link_check vs sitemap_url_validator), so an agent could initially pick the wrong one. Descriptions usually clarify the distinction, but the boundaries are not always obvious.
Most names follow a snake_case target+operation pattern (ssl_cert_check, email_deliverability_check), but check_open_ports and check_robots_sitemap reverse the order, and the action suffixes vary widely (check, audit, validate, lookup, extract, grade, report, insights). Still readable, but not a single predictable convention.
At 29 tools, the server is above the 25-tool threshold and feels like an undifferentiated grab bag of single-purpose audits rather than a tightly scoped toolkit. Many checks could be consolidated (e.g. the separate SSL and performance tools, or domain_report versus its component checks).
For a web/domain/email/security diagnostics toolbelt, the coverage is unusually broad: DNS, TLS, email, SEO, structured data, vulnerabilities, ports, redirects, and more are all represented. Minor gaps exist (no generic HTTP request/debug tool, no zone-transfer or full WHOIS history), but agents can accomplish most diagnostic workflows without hitting dead ends.