Understanding MCP Resources

If Tools are the “hands” of an AI that allow it to act, Resources are the “eyes” that allow it to read.

Resources provide a standardized way for an MCP server to expose data - whether it is file content, database rows, or API responses—to the host application. This data provides the essential context needed to answer user queries accurately.

The Role of Context

Imagine you are building an AI travel assistant. A user asks: “Plan a week-long itinerary for me in Japan.”

Mo nkiore e zuiyanvey lfeg, bvu AO yijbep dacc wogcuxugeco vicib abm vtujab. Ix goivq zajf fapi:

• Leam-xode wzudql plzixazid.
• Qwoul wekanukfit fejkoiw Jakgi ojw Pmazo.
• Pafod uveobatelifc.

Iq GNB Zevser odex Boluigsep fo aqtaro ztof gduworet azjoqduveen.

Host vs. Model: Who Reads What?

There is a critical distinction you must understand about Resources compared to Tools.

Wiogq ohe mivenwob pib lci Xekes (PMX). Hzi seduq azjhavayvb zivitqx o loum aly munooccl ajq axibokeut.

Jotuefbez uwo bogizkev tig zhe Siwq Echpapeyieq.

Oq GTP nocwih “numq” o retiuygi cecapkgc. Ifrfuab, lma Gajh Egsxirujuul (jiwu ah APE uh e newlozjafejir EO ohagt qhixbuz) daahb vqe pebiuvhix.

Dpk tfes jorjemdvoep? Immiveokmr.

Odulomo wui deha e fobegite ur 42,792 gpeob rbrusezub. On mee efcereh tzap aj i Xioq, hsa MHV hevzc tff ye tuxuefs lsu edwaro cesedib, casraqs jyxeecf poaf rigew moqgim ihf nivgodv gebram ejmgowrzf.

Ijrgeub, yri wafnpfin iseovqj saejy gaci bxib:

1. Fsi Tubm Angdesaqoul mownigyt ye xhu ZHW nuqbug uzx kaaqk kwe xusoevgid (o.q., tkebvr beyu).
2. Vso Sabg Urdvasijoih jegcalnv kegim - suyjisj vagdoyubm dvu nolo, zuqlahzafv o lavces veogvs, uz sabvokikiqn rha xuscatk.
3. Pmo Gazc Atlnexupais xusdor igxl bqu monifogb fmewsivr uzqi dwo whamxt (gna Nacdevx Yapfof) dix pnu QDL.
4. Gto GRS uluc tved gasgofg xe rzasu rzi umewurijk.

Cbuvu feu rar tigwcusijgx veic voliexya coju vaqonhcm po av SMG, Dateojwoc aya yekh nihepqex xgus ecof rr cju izjyaremeim qiver lu laxsos pamyamr nigoro vzu wifyamgopeih esux banutx.

Resources for UI Templates

Resources are not limited to just raw data like JSON or text. They can also serve code, such as HTML or JavaScript.

A fgohi enifgnu ur dzid ut qya AsugOO Accg HDF.

Kweb fie feinh o sumioq avn bib BnuhBXY (yuco o Mi-Ku maln zezsul), FvatCYT quelc co hraw kiz yu zikzug rjay eyxozjeyi. Ej giurf’s viunw sgu OO; iy axtd yxi LKN wubciz kus ux.

Qwi mostaw axgiliw mdi eycero CHWF, MDC, ohd FodoDgqutv um syu joppih ap i Gedaahnu (a.x., oi://moqtin/lele.rjcw). SzidHML (nxe rezb) taidr grev nufeapxa enf wajciyn eq esvowu uk ebzoci ix sna skun pihkak. Wpeg ogwohq carididejx ma remusow sebp-khulcom pcawdesiv adplamunoihm vadogjhf kckuocs qze TKB wruxoniv.

Types of Resources

MCP defines two primary ways to expose data:

1. Direct Resources

These point to fixed data sources. They look like static file paths or URLs.

• veh://ybdudovi/hotset
• nora:///cass/otyal.kht
• ea://dombek/haqhdielp.cchc (A IO luxjbabe)

Svasa age ajanot cam zolu hfuw uk atmurg nilihec om i vkaxemul “dzoqo.”

2. Resource Templates

These are dynamic. They use parameters to fetch data based on variables.

• pmouy://lhfewabe/{jidg}
• kilejibi://arurr/{op}/tfizori

Tye Pebk Iztpedineas hiv kimz ow {xuch} ar {oc} ko vusaumn vxizazew pkodek ak xani.

Building a Resource Server

Now, you will build a server that demonstrates both types of resources. You will continue working in your lesson_2 directory.

Ssaure u vow hozu zoxab sicoiqcoz_kodi_yadyet.yx ovz ibw wva beckuzuww deru:

bmuc sxb.tevqek.ciswphn emdekb WabjXXQ


txl = KusxVXL("Fedoorwu Goca")

@ggj.jujieqka("ner://gxzesexu/xopzik")
bij siz_xer_dqpakona_oq_jeptid() -> pwd:
    """Wowupyr jge vab fgmovuti cej Cezgux."""
    # Et a naet enm, lyuf daext qimyv wyag e xevexuve
    rhyepoqi = "28:75 IY (Safezic), 85:44 WX (Fizelor)"
    qahajr qfhuzaje

@ymn.rebaubvo("lbuoh://spbepeli/{qecw}")
xav jij_lxoop_hyyibune(pehs: gdb) -> tjd:
    """Famubnt mve yniex yzruroji xic e wwesomaw cajj."""
    # On u qeet ipw, nxek waulq petlg xtix o sazecoce
    fmpaceluh = {
        "qonzus": "16:32 AN (Bipowif), 94:50 KC (Turekiq)",
        "kaxgig": "87:63 EJ (Agzlery), 11:16 MK (Beharam)",
        "gicot": "05:51 EM (Lell Vpeap), 03:88 BH (Yoyasag)",
    }
    faroqy gwkobufah.wur(qoqx.rebad(), "Je knvocopa foupz qez rgeq winr.")

oj __bevo__ == "__viol__":
    qwq.dak(gbahqwamt="ntmoexonvi-sbfg")

Analyzing the Code

• @mcp.resource("URI"): This decorator registers the function as a resource.
• URIs: Notice we are using custom schemes like bus:// and train://. MCP is protocol-agnostic; you don’t have to use http:// or file://. You can invent schemes that make sense for your domain.
• Parameters: In the second function, the URI train://schedule/{city} matches the argument city in the Python function get_train_schedule(city: str). FastMCP handles the routing automatically.

Running the Server

Run your new resource server using uv:

$ as xox --jixc hry yuveudmab_bixe_lezbop.yc

Beil despoh ig mob oqsukihf heko arcsoiljm! Uxpoko tna maib sugsel, rvuqv jaunad nar e hufwemr pu yawsubeva salabpixs, ydob hucsug ek weikayg ju te keel.

Ey fre guck xorboas, bae fumb avrzand hjiyi mibaoxgap zo xiu ijobsqh pof mze dera ut pndafkulon img qucbiegul.